And also last week I stayed the night with her and we stayed up and watched movies, cuddled, and kissed all night. Then the next time we hung out, no kiss, nothing. I don't fucking get it.
Yeh bro, this sounds like a rebound to me.
If you go all lovey dovey on her, she is most probably going to get wierded out and stop sleeping with you.
My suggestion is to let actions speak louder than words. There is no need to have a talk with her right now especially when everything is going fine. Just ride it out. You are trying to "claim" her by making her commit, because of your insecurities, because deep down you are worried you will lose her.
IF you want to keep her, you need to be ready to lose her, be ready to walk away. Just live your life, focus on your goals, and when you're spending time with her, focus on having a good time. Keep it interesting by spicing things up (do different activities together, have sex in a different position, basically do anything to keep things from getting stale).
Then just naturally let things progress. You will probably end up having the talk at some point, but it will seem more natural when you do, and if you do it right, she'll be the one to bring it up, which is ideally what you want.
However, I am pretty sure you wont follow any of my advise above, and you will probably end up losing her because you will scare her with your eagerness. Experience is the best teacher, or so they say.