How do I talk to this girl?

I am aware that this question has been asked many times before, but I'm asking it again. My issue is this. I'm 17, nearly 18, in my last year of school. There's a girl in my year who is, without a doubt, one of the most gorgeous girls I've ever seen. She is also a really nice person and is in one of the sections of my friendship group, so opportunity to talk to her is not too difficult. But, I used to be that kid who everyone bullied, and that was the time when I sat next to her in year 8 (I was 13). This meant I was shy and we rarely talked. This wasn't helped by her stunning looks and great personality because I felt like I'd never have her. I rarely even made eye-contact. Since then I've made friends and become far more confident in who I am. I have long hair and wear a leather jacket, I don't take no shizzle, But I still find myself unable to talk to her. It's partly that she sucks confidence out of me and makes me weak at the knees, but also that I have literally nothing to say to her. She's one of those people who seems to make so many natural pauses in a conversation that it consists mostly of silence ;/ She's great and we can exchange a few sentences, but she doesn't have much to say to anyone. She is a relatively popular girl, in our group, but some of my friends have the same issue with her. I tried sending her a facebook message the other week saying "Hi, I felt like talking to someone different :) " - Which I now know would have worked better as "Hi, fancy talking to someone different?" She's seen the message but not replied. But I can't change the past, just thought you may as well know all of it. Though she's spoken to me a little recently.. What can I do to be able to talk more to her? It's really an issue of stopping her natural silence bringers and having more to talk about... I must seem so whiny but thanks in advance xD