Does this girl like me?

So here is some background info:

I'm 16, so is she. We both attend the same school and have been friends for the best part of 3 years. Recently I have had my hair cut from long to short and she said that she really likes it. Anyway, I asked her to prom about two months ago and she said yes:) I did think that she liked someone else, but at a party last night we basically spent the whole night together and we just chilled together, we sat in the garden for a while alone, just talking, but I didn't make a move (sort of regretting that) just talking about prom and each other, I always thought that she was too good for me but I am having second thought and I am now thinking I may have a chance. I'm just not sure what to do next, I really like her and I am not too sure if she likes me, but surely there has to be something there? Any advice about what to do/say to her, or whether you think she likes me or not will be much appreciated.