Can't tell if she is interested??? Help :(?

[Nick]

Ok so I'm a sophomore in high school and I a like this girl a lot. Recently I have had the courage to say hi to her everyday when she walks into my class. She responds with "Hi Nick" everyday and gives me a smile. I caught her looking at me when someone else said my name once. There was even one time when she bumped into my chair and started laughing saying sorry. The day before vacation, a couple minutes after I said hi to her, she was sitting down and started talking to me. She didn't give me one word answers or anything when I was talking to her, she was trying to push the conversation along. This was the first legit conversation we had together. She initiated btw. It sucks though because that was a day before christmas break so now I can't talk to her now until next thursday. I followed her on twitter a couple days back and she didn't follow me back. We only talked once so it's understandable but I don't know if she is playing hard to get or maybe she isnt interested. Thanks