Friend her on Facebook and be like, "Hey, we met at that thing, I really love your music," etc. If she counts you out because of something on your Facebook then that means she's not right for you. When it comes to this stuff you've got to be real first and foremost or else people start taking action based on falsities. You can only present yourself as you and see if she responds--otherwise there's nothing you can do.
The only other advice I can give is, if she doesn't look like she wants to connect on Facebook and you've got no other ways to actually spend time with her, put her out of your mind. I've been in the "she doesn't even know I exist" crush-type position before and it only gets worse the more time passes. You psyche yourself out into thinking that she's perfect when you're really just filling in the blanks and constructing a fantasy image to obsess over. I'm not necessarily accusing you of doing that, but I know I've done it and it's a very common thing for people to do. If you can connect, go for it in whatever way you can. If you can't make it happen, you've got to let go, and the sooner the better.