Helping 12 Week Old Kittens Grow?

Some weeks ago I convinced my grandparents to let me keep two indoor kitties for the FIRST TIME!! It has been about a month and a half, maybe two months since I started keeping them in the house. They are 13 weeks old, and no I did not rip them away from their mother! At first I kept them inside only at night to prevent wild animals and such from feasting upon them (it's a harsh way of putting it but the truth), which is the usual fate for kittens where I live. They were born during my birthday party in my brothers closet, and then moved outside in the barn and not even a few days later their mother hid them and they were not seen for another five or so weeks. One day I heard constant kitten meowing over the TV and music so I ran outside and realized it was coming from the barn so I opened the door and there was little Silky. She ran to me and the first thing that came to my mind was "Oh my god.." because she was so horridly frail and malnourished and frankly just insanely tiny. She was a bit fluffy and I could still see every single bone in that poor baby's body.  After I found the other three, all just as skinny, I immediately grabbed some kitty kibble and water and gave them and they all ate it right up.

So the next few days I fed them, watered them, showered them with attention, etc.. and their mother moved Silky and Link out of the barn to under my mom's front porch. I also noticed two of them very suddenly were incredibly sickly. They couldn't walk or anything.. and it was heart breaking. So I took their mother to them and she completely ignored them and kept going right back to Link and Silky and to be honest it was INFURIATING!  I kept trying to feed them and give them water but they just layed there and the next morning they had passed on to kitty heaven..

Anyway, Link and Silky both seemed to be in good spirits, even though they were covered in fleas and their bellies were badly swollen from worms and they were still skinny! Within the next few weeks I had them wormed with kitten dewormer, gave them regular baths to keep fleas at bay, and started them on wet food.

After some research on wet cat foods and such, I found out that cheap foods were cheap for a reason. They were filled with fillers not nutritious meats and such, so I started them on the best food I could afford, 4health wet food (more on this later).

Now at 13 weeks they no longer visit their mother unless I'm taking them for a walk outside and they are worm and flea free! They both use the litter box well (Silky wouldn't use it for weeks, she was AFRAID OF BOXES) and they're crazily rambunctious and snuggly.

However I am concerned about some things.

(I guess this is my site intro too?? Sorry for such a long back story)

YOU CAN SKIP TO HERE FOR THE MAIN QUESTIONS! 

1. They're pretty small.. Could this be genetic? Their mother is TINY for a full grown cat and always has been. Is there any way I can make them bigger?

2. 4health cat food reviews? They eat about one (13oz i think)  can a day (together) and I add a little bit of coconut oil or olive oil to their food because I've read that it does kitties well.

3. Still a little skinny, but full of energy and very happy (I think??) and no poop issues. How can I add a little bit more fat to them?

Thanks    

Don't do anything to make them fatter. They'll grow as big as they're meant to grow, as long as you're feeding them well. Sounds like you're doing great!

You'll want to have them spayed/neutered soon, as females can go into heat as early as 14-16 weeks and I'm sure your grandparents don't want a cat howling and spraying all over indoors. The male probably won't come of age until at least 6 months so it's not such a hurry with him.

It sounds like you're doing great! If mom is small, the kittens might also be destined to be small cats. As long as they're healthy it's nothing to worry about. The amount you're feeding sounds good, but if they seem hungry for more give it to them. Kittens should eat as much as they want.

@momto3cats & @Willowy
Thanks, guys! I haven't started them on dry kibble yet, does anyone have any suggestions? I'm sort of on a low budget though and I'm worried about food quality I live in a small town and there is no PetSmart or Petco or anything like that.
and I've already started looking into that. The humane society here has a low cost program and they're both getting spayed/neutered as soon as they are big enough, because apparently they are too small, and I get the money.

Hello I was wondering linkandsilky what you could tell me more about the olive oil? We just adopted two kittens as well one is 1.9 lb's. We are also feeding her iams kitten food with a 1/2 teaspoon of Viralys we got from the rescue. What exactly does olive oil and coconut oil help with