Hey, so I have a question. Just needed help with a reflect about a situation, I want to be smarter with.

At my school, I have met this girl several times at our school-bar(That is open every friday, and I go there every friday)

She is always kinda lightly dressed all the time, and she is quite confident. Anyway, this friday night we talked a bit, played beerpong, etc etc. And we kissed, she was kinda very agressive, biting my lips etc. The funny thing, is that when I flirt with her at the other fridays, she kind of wanted to friendzone me all the time. But this friday she wanted my attention, and started flirting with me.

Anyway,
She asked if I wanna go to the bathroom with, and I did. We kissed, and kissed and then I directed her hans in my pants. but then I touched her pants, and she removed my hand, and didnt want that. But we stilled talked afterwards, and kissed. etc.
She then said something about a boy, that did not end. A and she went home.

She did not want me to be facebook friend with her, which was very very wierd. And that was before we were in the bathroom togheter.

I think my mistake is that I did not build enough trust and comfort and that she felt like I only wanted sex. But maybe she has something going on at home.

1. What do you think was my mistake, with the limited information I gave you?
2. If a girl knows that you only want sex with her, does she reject you? (I have always kind of thought about it) Or does it depend on the girl? What should she be thinking about me?

3. I always, always have problem from going to the sex-escalating after kissing. Any guide on what I should do here?

Thanks in before hand!