Is variance in growth rates common in kittens?

As said above, she needs to be fed every 2 hours around the clock, feeding one drop a time into her cheek. You don't have to force her mouth open all the way. You can wrap her in a towel like a burrito to restrict her movement. She has to eat regularly if she is to live.

I wonder if kitten Paris would prefer to be fed on one side of her mouth? I have a cat who will only tolerate syringe feedings/meds on her right side. If I do it on the left side she struggles..have you changed positions and tried to see if she prefers one side over another? I would put the syringe in the mouth at the corner where lips meet. move skin up a bit and do a drop on her side of mouth. Maybe its too cold? Have you warmed it up? some people put the bottle or container of liquid in a bowl of hot water for abit to warm it up. you dont want it ice cold. Don't give up. You are doing a good job! Maybe try goats milk? Someone on another thread posted a homemade concoction that can be used-maybe they will post it here...not sure what else to recommend..keep up the work!

Thank you @foxxycat  I needed that motivation.

I'm covered in formula as I write, but I actually got her to eat. I took her out of the room with mom after she was left alone for two hours between feedings. I put her on my chest and elevated her head with my arm and it actually worked. I ran to the drug store and bought eye droppers because I realize the syringe may have been too big. Lil Paris resisted for a while and had a screaming match, but once she was done she started eating. She does prefer to eat from one side of her mouth and after half an hour she started purring and licking up some of the formula that spilt on her paws. She is still breathing heavy, but I feel like this little girl may actually have a chance. I will still be calling my vet in a few minutes to ask for advice and if I should bring her in. Paris is currently cleaning herself and when I give her the eye dropper she started feeding from it. I will update once I hear from the vet or after the next feeding.

She took approximately 30 ml today give or take how much ended up spilling. 

Little Paris sleeping in her nest until her next feeding. 

The vet said that I should keep feeding her, but to bring her in if she stops eating, starts breathing very heavy, or drops more weight. I am going to observe and nurse her today and make sure she gets that enough KMR in her. I have fed her twice in the past four hours, but now that she is eating I am going to try once every four hours. If she starts crying for milk then of course I'll feed her, but I am trying to get her on a routine now. Should I put her back with mom in order to be cleaned, pooped, etc. in between feedings? Or should I try hand rearing her until she gets more weight on her? I don't think mom will feed her at all because she has only touched her a handful of times in the past day, but she was cleaning Paris. 

Put her with mom and see if mom starts cleaning her again.  One this kitten is on the mend mom should begin taking care of her.  Either way it's good for the kitten to spend time with mom and siblings.

do you have a heat source in the basket?

Also I saw someone mentioned that you can use a makeup sponge to have her nurse the milk out of it? Do you think she wants to suckle? I saw this mentioned in another thread yesterday-eye dropper works. Sometimes you have to find out how they prefer to lay but of course always have her laying on her belly. Sweet wee one. I have never had a kitten that young and I would be so very nervious...keep up the good work..

Good to hear she is nursing and eating from you! She can absolutely be saved. You have to force feed her until she gets the hang of things, which it sounds like she is once you took her to a different room. If she gets lethargic, put honey on her gums to perk her up. She should get past this little crisis soon! [emoji]10084[/emoji]️

Is it possible to feed her a bit more frequently for now? I wonder if every 2-3 hours would be best since she is struggling. And that should be every 2 or 3 hours from the start of the feeding, not when she finishes.

So glad you got something in her!!

Her breathing got worse so I called the vet and I just sat through the most frustrating and unproductive appointment i have ever encountered. The doctor weighed her on an adult cat scale and she came in at .6 pounds. He told me he didn't believe that a kitten could drop weight that quickly and that she was dehydrated and malnourished. I told him I tried feeding her, but he kept telling me to buy milk. He took her back for fluids, dewormer, and antibiotics, but he didn't know what was wrong. He said she appeared healthy. He then continued to say he didn't charge me for the fluids or dewormer and that he saved me $60. I feel like he had no idea what he was talking about and now i have to bring Paris back home, even though I'm convinced she isn't breathing right. The nurse had said it was possible that she could have an infection and the antibiotics would take care of that.

I'm frustrated, but all i can do is take her back home to feed her.

Yes, perhaps the antibiotics will help, and she needs feeding by you about every 2 hours. Are you using KMR or goat's milk?

Yes, unfortunately many vets are not experienced with baby kittens.

Fluids, dewormer and antibiotics certainly will not hurt her and hopefully the antibiotic will do her some good.

If her breathing continues to be rapid, I'd suggest having an x-ray taken (the whole body should be done in one take.) I'd mostly be looking for evidence of a hernia (particularly a pericardial diagphramatic hernia). But, there are other things an x-ray could reveal.

Have you noticed any coughing/wheezing or sneezing? Are her eyes clear?

I am using KMR, the GNC brand, I started feeding her yesterday and started again today. I give it to her slightly warm and from an eyedropper into the corner of her mouth. I had fed her every two hours for the first six hours before I took her to the vet and immediately when I got home. She is with mom right now and gained weight since yesterday. She hasn't pooped or peed from my knowledge so the weight gain may just be temporary, but I am continuing every two hours now while leaving her with mom in between. 

That sounds like a great plan. I think every two hours around the clock until she is stronger, and then you can ease off a bit.

Her eyes are clear and no signs of coughing or wheezing. She will make a weird noise when she has milk in her mouth and isn't swallowing, but I think that is her just trying to get used to feeding from the eyedropper. It just worries me because of how fast her little body moves, but I am going to focus on getting her fed and see if that helps with her breathing. It could just be from her being malnourished and her body trying to keep up.

Thanks everyone, I'll keep on her new routine and see where that takes us.

The three healthy kittens are all growing rapidly and mom seems to be doing her job well. They have hit some kitten milestones, like learning how to walk, attempting to eat food, and figuring out how to climb. They are all healthy and happy however, Paris still requires hand feeding and seems to be doing well with the formula. I am making sure she is getting in the 88 mls per day and she is back up to 11 oz. When she is done eating I put her with mom who will clean her up a bit but for the most part still leaves her alone. In between feedings paris is snuggling in a kitten pile with her siblings if I place her there or remains the outcast and sleeps alone. She has put on weight but is still so little and has no interest in anything besides sleeping. When should I expect her to resume her normal antics like playing with her sisters or trying to crawl towards mom when she is left alone? Before she dropped the weight she was acting like any other kitten, but now she is far behind and I don't know what to expect within the coming days. I am going to try to make sure she gains the necessary amount each day but should I be seeing more from her besides weight gain?

As she gains weight, you will need to increase the amount of KMR you give her.  remember 8ml per ounce of weight divided by the number of feedings in 24 hours.

At this point, I am positive she is dying. It's so hard coming to this realization, but she has headed down hill so fast. Yesterday she was purring and moving around, but today she has lost most signs of life. Her breathing is rapid and there are moments when she breathes out in a shudder and forces herself to take the next breath. She has gone limp and won't pick up her feet and can only hold her head for a second before letting it fall. I have tried feeding her, but at this point she can barely even swallow. Mom cleans her and keeps her close, but Paris is so weak that she flops over by even the slightest push. She is breathing so hard that I know she is trying to stay alive, but there is nothing else I can do for her besides keep her warm and comfortable. 

Based on your description, she has either aspirated and/or has a congenital issue (cleft palate, pericardial diagphramatic hernia...)

Is her breathing raspy or noisy at all?

Kittens can breath heavily due to pain. Is she constipated? Has she had a bowel movement? Have you burped her (yes, like you would a baby)?

If I put my ear to her mouth I can hear her breathing, but besides that it is mostly quiet. I do not know when she last had a bowel movement because she is with her mother most of the time. I worried about that too and tried stimulating her to pee; I would get diluted-yellow pee, but no signs of poop. I have tried burping her, but because she was so small I couldn't tell if it worked.

Have you been feeding her every two hours?  You can try putting some honey on her gums to perk her up before feeding as a last shot.