There's a girl I really like, and want to go out with her, but I don't know... help!?

There's this really cool girl in most of my classes, and I like her...alot. and I think she likes me, but I can't tell. I got this note from someone in her little group of wood-wind players asking if I liked her. I'm also the only boy from our class she invited to her bas mitz vah (no clue how to spell it). we're also good freinds. mabey she invited me to her bas mitz vah because she thinks i'm gay? I have no clue. some times I kind of see her looking at me, but look away. I really, REALLY, need help. Thanks.