Does she like me?

Ok so this girl I like is really shy and sometimes I think I'll see her looking at me out of the corner of my eye but if I look up to see if it is me she as looking at she usually looks away. If we make eye contact she usually is the first to look away and sometimes if I do look at her while she's looking at me she'll have kind of a blank, emotionless face, what does this all mean, does she like me? Also one time I saw her look back (towards my general direction) and she was in the corner where the tv was, since we were watching a video I was looking in her direction and when so when she looked back we looked at each other and she quickly turned and looked away. I saw her outside of school, I said hi to her and she looked at me gave a big smile and a really enthusiastic hi but the conversation was short and she ended it (the again I think she had to leave soon) and then I saw her at the end of her show (it was figure skating) and I was looking at her as she walked towards me and she said bye with a smile on her face. Wouldn't she have tried to have a conversation if she liked me or is it possible she was just in a hurry to leave (she left right after she said bye to me and didn't say anything to anyone else). Then today she said hi to me and waved with a smile on her face but she passed by me a few other times and didn't say anything to me. Also since I have classes with some of her male friends and am somewhat friendly with them i'll occasionally go up to them and ask them what class we have next and just make small talk, since her locker is near he friends locker she can hear what I say and I'll often see her looking at me as I'm talking to him (I didn't interrupt them though) and I noticed that her and her friend were talking but then when I got there they stop talking and was just an awkward pause before one of them said something. Is she looking at me because I'm near her and gets quiet because she's afraid of say something that could make me think bad of her?

Also we are both 17 and she is shy and doesn't talk to many guys except a few who are her friends. Thanks.