What is kitty's body language telling me?

OK so as a first time cat owner I still get nervous about reading my sweet kitty's body language. So here is a video of her hanging out with me....

 

Can you kitty body language experts help me out? From what I can tell

- Kneading my foot and leg means she is relaxed and trusting

- Belly to me means she is trusting

- Eyes half-closed means she is relaxed

- Her face on my leg definitely means trusting

- Tip of tail flicking... bad sign?

I went in for more pets of cheek and head after this video and she seemed to love it, plopping down more than once to lay on me. But I stop pets when I notice the flick of her tail in case it means she is starting to get annoyed. She has nipped me once or twice - VERY gently - as if to say "please stop" when I thought I was reading her right. 

What did yall think? 

I'm no expert but I think I've read somewhere that the tail flick can also mean that she's really excited.
Cats really can be confusing. [emoji]128514[/emoji]

Cats usually have a 'stimulation threshold' which means that after a period of stimulation, (stroking, petting, any kind of contact) they get agitated and will let you know it is time to stop. Gentle biting, or growling, is a 'nice' way of telling you. My Chrissy would latch onto your arm and draw blood. There are definite signs warning you of reaching this limit......swishing or flicking of the tail, a puffed tail or fur standing up along the back, growling, and right before they attack, dilated pupils. I used to play a game with Chrissy that involved pulling a feathered wand in front of her. An instant before she would attack, her pupils dilated and I would whisk it out of her way. She always looked like "How did she know I was going to jump RIGHT then?" The swishing of your cats tail means she is getting agitated and you should stop all physical contact for a while. It does NOT mean she is temper mental, or 'mean', she is just warning you she is done playing or getting messed with and wants you to stop. There are MANY actions a cat can use to communicate, it is well worth while to observe and learn. Your little girl is beautiful by the way, you are lucky to have her in your life. All the luck!