? Without seeming desperate ?

Ok so there's this girl I went to middle school with and high school. She was in quite a few of my classes and we've spoken but we didn't hang out out side of school nor did we belong to the same group. I've always thought she was beautiful smart and a genuinely good person. However I also had a feeling she was gay because of the way she looked at me but I just attributed it to her being nice. Anyway I'm 23 now and she is 22 we've gone our separate paths in life but remained friends on fb and every now and then she crosses my mind and I ask her how she is doing .in 2010 I guess we spoke and I kind of got the feeling even more that she was gay but then we quit talking until last month... 2012... I said something and then ended with" I don't know it jus made me think of you hope your doing well " in response she said... " I was just reading through our past conversations and I don't know it's just interesting had I not been so surpressed by Christian and heteronormative culture and you had been more forward I think I would have become more myself a lot sooner"... ever since then I haven't been able to get her out of my mind... I got her num from my sister which se didn't mind... but I don't really text her cz I don't chase women hence the looking desperate... however I did let her know that I liked her an she did tell me that she was in an open relationship... but it kind of seems like she is in a relationship like they live together with no title... She told me that she was always shy around me... anywyas I really want to tell her how I feel and get to know her better... but I don't want to intrude... besides we haven't spoken since she told me that... we do have some chemistry that much is for sure... I just don't know if I should say anyway I feel like it'll look desperate . Because I've already kind of told her and I don't to be a broken record...  
Besides we are not on a level where I'd call... or even know her real well

I'm not sure exactly what you are asking... you like a female, you want to be with her, but yet you are not willing to chase her?

She isn't going to declare her love for you out of nowhere if that is what you are waiting for you are geatly mistaken. You need to put yourself on the line, risk rejection, and hopefully have a positive outcome. How about inviting her to do something, movies, club, bar, bowling, pool, or any other type of fun activity that one would consider a "catch up" date.