Sweet kitten getting more agressive; normal or is she not happy?

My dear, sweeeeeeet little Jasmine, my little rescued one that I nurtured back to health... She would accept anything; I'd pick fleas out of her fur, with fur and all, and she'd just lay there and let me work on her. She was about 8 weeks old at the time. A purry little angel!

Now, at 11 weeks, she's very outgoing and social, will come when I call her, and purrs alot still. Very cuddly and nice.
However, she is definitely into alot of play, very wild at times, which I know is normal. But she is also starting to bite now and then, and will let us know if there is something she doesn't like; like if I pet her legs or stomac, she will sometimes bite me. Just starting to become somewhat aggressive.

I wonder if this is abnormal for an otherwise sweet kitty, or if it has to do with her age; starting to grow out of babyhood maybe???
Also we have a new kitten now, please see my thread called "Input on how we are introducing our kittens to each other?" I'm wondering if her behaviour is the result of the stress of another kitten in the house... Or is she just not happy here? We have tried our best to be good to her!

I really need some encouragement, I'm so stressed with all these issues, and with trying to help our kittens getting used to eachother, keeping them separate etc. To top it off, one of my dc may be allergic to the cats and the issue of whether we can keep them...
So sorry for being such a worrywort these days, I just need some help to sort it all out, then soon I'll be my happy self again.

Hi, sounds to me this is a common case of she is stressed out by the other cat. My advice would be to engage her in some play therapy. I've been doing it with my cats, and while it has not always been 100% pleasant, it's been a better environment.

HI! You are not experiencing anything out of the ordinary and it is good that you are seeking advice early to stop these stressful behaviors. A early introduction to a new cat is better, though many times any animal will feel threatened by this. Always make sure you give them the individual attention you did prior to the introduction and keeping them apart for to long can often cause more aggression towards each other, they often feel punished or something is being kept from them then.
All kittens will test their bounds with you, biteing, scratching, jumping on things they normally don't care about other than to get your attention! Some need less aggressive training, such as blowing on their face if they bite you. Some more, a water spray bottle, or even a little taste of their own medicine, just enough of a teeth-contact on one of their ears to make them look at you like" What the heck was that!". This is something that shows them how we feel when they do it to us, but is only necessary in extreme eggressive behavior and only during play.
The best relationships in all aspects are when there is a balance of respect and love! All good behavior that is asked of them should always be rewarded with a treat, anything from a good kitty message to a Pounce depending on what they appreciate the most!
Goodluck!
Cheyenne & Sweety