Should I forget her or try to make something of it?

I am a sophomore in high school and there is a girl that I kinda like who is a junior. She is pretty popular and I think she has a boyfriend but I'm not really sure. We have one class together and at the end of 2 weeks ago, she began talking to me. We had conversations and she was the one really initiating conversation and physical contact. The past week, some days she said hi to me and smiled when she saw me and other days she completely ignored me. Regardless, I don't think dating her would really even be possible since she might be in a relationship, she probably doesn't like me, I see her everyday and will for the next two years give me a constant reminder of embarrassment if I decided to ask her out and she rejected me. She followed me back on instagram and I sometimes notice her looking at me but Im just not sure what to do. How do I get over liking her so we can just be friends or what should I do?