Should I try talking to her? (somewhat long, needed to vent this out, please read)?

Ok, there's this girl that during the school year, I had a GIGANTIC crush on. Like, there has never been a girl that's made me feel like that before. I never had any classes with her, I only saw her in the hallways, but wow was she gorgeous. I know I can't really judge based on just looks, but she seemed to be somewhat interested in me too. We made eye contact a lot, and not like the eye contact you make with people as you walk past them. She'd always either turn around, or to her side and look at me. One time her and her friend kept turning around and looking at me as they were walking down the hall. Another time she kept turning around and looking at me on her way to her class, and before she went in, she turned around, looked at me, then walked in. This one time I saw her, and after our eyes met, I looked away, then I heard giggling. She's even smiled a few times, but being the shy, somewhat unconfident kid I am, I assumed it wasn't directed toward me. There was just a gut feeling that she might have felt the same way. I never mustered up the courage to talk to her, but on my last day of school, I actually smiled at her, but she didn't see me (I was in a huge line waiting to get my cap and gown). I added her on facebook (she was tagged in a friend's picture), and sent a private message to her. Here's what it said "Hey, we don't really know eachother, but we sometimes saw eachother during passing periods. I'd like to get to know you better, nothing is wrong with making new friends right? So, what's up?". It's been about a month since I sent it, and no reply. The thing though is that I think she might just ignore private messages altogether, because she has a lot of facebook friends, so she probably just wants to avoid spam. And if she read it and was creeped out, she probably would just take me off, but she hasn't. I've tried getting over her, but lately, I started dreaming about her again. I had a dream we were singing some love song to eachother (kind of weird hehe), and I had a dream where we went on a date together. I kind of want to try instant messaging her the next time she's online, but I get so nervous. What should I do? I don't really think I'm bad looking or anything http://a5.sphotos.ak.fbcdn.net/hphotos-ak-ash2/74820_172279329455415_100000200473356_627249_670274_n.jpg