What should I Do about this girl?

Kay here's some details. I'm a sopre and so is this girl I like a lot. Thing is we have been like best friends since eight grade. We tried dating once right after but it didn't work out due to the awkwardness. She's actually quite shy to the point where she will only talk to a few people. I have the same problem with shyness but I it's not that bad anymore. I'd like to ask her out before the school year is over but whenever I try I get really nervous and just end up having a conversation with her or I give her something and then run off. Funny thing is I was able to convince her to go to our school's winter ball and again for our sopre/freshman banquet though we only went as each others friends. She knows that I like her but I can never see any signs that she likes me the same way (I have bad eyesight add in the fact I end up watching her eyes only when we talk but I can't read people at all) that I do. Now days I can only talk to her for a few minutes cause school things have been keeping me busy so that's like a major problem. Someone please help me!