Does she like me back?

I'm 21 (female) and I've identified with being straight. Or more like, people assume I am. I had a boyfriend for almost three years, he's the only person I've kissed or done anything with. Things were fine, we drifted apart, we broke up. I think I'm bi, because I've had crushes on men and women and am pretty private about my thoughts so people don't know who I like whether it's a man or a woman.

Now, I like this girl. I've liked women in the past, whether they're in real life or an actor or whatever, but this girl is someone who in theory I *could* have a potential chance with. She works at the same health club I work in (I work at the pool, she in the children's programs). She's 25, really cool, and I like her. Her name is Lauren.

Why aren't I asking her out? I don't know. Well, I do. I'm not sure if she's a lesbian or not. I know she was in her friend's lesbian wedding, but that doesn't mean she's one. I was thinking I'd just talk with her more and more when I got the chance to, since we aren't really friends (I am her friend on Facebook, though). Recently I found out that she's moving to Hawaii for up to a year and will be leaving in the middle of January. We're in New Hampshire.

I want her to be my girlfriend, but I'm not sure I'm brave enough to do anything. I'm an introvert and don't open up hugely to people. Coming out as bi would be enormous, even though my family would be okay with it. I think maybe it would be stupid to try to be with someone who's going to leave in a couple of months. Then again, my boyfriend and I had a long-distance relationship (he was in college, I wasn't) and we sort of made it work.

What would you do in my situation? Should I somehow let her know I think I'm bi and see what she says? I'm not sure how I would tell her and I don't think I could get up the nerve.