There is a girl I'm not sure if I like (I've always thought I was straight) and if she likes me back

Ok, so this started 3 months ago at our prom night. We weren't close friends before, but somehow we spent that night together. I mean at a prom. We talked, danced, and sit with each other. And that night I saw 'something' in her eyes when she was looking at me. She said I looked really pretty, then blinked to me once, when it was dark around and we were just staying and listening to music. I can't remember everything from that night, but it was the first time I started to look at a girl in different way and I thought I could feel the same from her. Since that night we've been spending almost all the time in the school together. I don't know, I think I can see some THING in her eyes, but not sure about it. She touches my hands or my back often, like yesterday - it was the last day of our schoolyear - and when I was making a movie, she took my hands to change the direction but she didn't want to take the camera, she was just holding my hands. she was talking to that camera, but I had a feeling that she was thinking about touching my hands at the same time. but well, I'm not sure if she really was.
and something about her. I've never heard if she was meeting meeting any guy before, so I guess she never was. I've never even heard that she liked any guy. and she always say that she'll never have any children and she's sure about. she has short hair, she doesn't like wearing skirts - but she's not looking like a guy, she just has a different style.
I don't know, I feel like we've been flirting all the time, but I don't know if it's just my imagination, or the truth.
My best friend told me a long time ago that she thought the girl I'm now talking about was gay. But I didn't think this was true then. Well,now I'm curious.
Even if she is into me, she does have no idea how do I feel - for sure. or she may just have some feelings about it, but I've dated some guys few times and she know about it so probably it's hard to figure out 'who I am' for her :P

I had a dream once, that we kissed. And sometimes I imagine that, and I want to kiss her, especially when i'm drunk :P but I have no idea if I could date her, and you know, have some sexual experience with her, I just have no idea, it's so strange to me. I don't like any other girl, I don't look at any other girl like at her. oh my god but I'd love to kiss her a lot.
whatever. what do you think I should do? how can I know if she's into girls or not?
I was thinking of asking her if she had a boyfriend before and if not, than to ask her why. but what if she says only 'just like that' or something?

do you think I'm bi?

She probably wouldn't reveal her sexuality so easily - in case she keeps it in secret. If I were you, I'd rather try to understand something from a playful conversation about this stuff. For example, try with a flirty compliment saying how if you were a guy you'd be hitting on her for sure. Observe her reactions carefully.

You could be bi-curious. She is the only girl you've ever liked, so don't hurry with the conclusions.

just say hey I know a girl that likes u but shez to shy to ask if ur bi or lez and if she says no say oh well dont worry bout it if she says yes say well that girl is me... works like a charm