Very confused, is she toying with me?

I’ve asked all my friends about this, and so many different answers I don’t know what to believe. Theres this girl at my school were both 16, I have had a mad crush on her for about 4 years (probably when we first met), I used to annoy her a lot, I didn’t really understand how to talk to girls when I was younger, until I had my first girlfriend when I was 14, now I’m quite a sociable guy. I asked her out when we were both 15, however, she said no and I was pretty gutted at the time, thought I got over it, she made it clear we were just friends. But latley, her best friend and my best friend got together, and we’ve more or less formed a small group at college, the 4 of us are good friends. However recently, me and her, we’ve gotten a lot closer, and the 4 of us do a lot of things together (We’ve got lots planned for Summer), and we more or less spend all our time together at school (4 of us), just chillin’ and talking really. But I find myself becoming unbelievably attracted in her, shes everything I’ve ever wanted in a girlfriend (probably all my past ones put together). I think she knows I like her (or shes just suspicious), however I haven’t said anything apart from a bit of harmless flirting. We do play around (like fight a little :P) every now and then, but she does keep her distance. She also hugs other guys at school, ones she barely knows at all, but never me, my other friend told me its because “she dosen’t want to lead me on to liking her”. Recently another girl at my college has told me she likes me, shes nothing compared to the girl I like, however it is SOMETHING. I feel lonley as well, its been about a year since I was last with someone. I can’t help but feel if I go out with this new girl, I will just regret it and wish I was with her, one of my friends said to use the new girl to make her jelous, however I don’t want to do that, cause its just plain wrong. She did ask me to our college prom =D (But only as friends, because “If our best friends are going we might as well too”). Any replies will be appreciated, I don’t want to ruin a good friendship if its not worth it, but I can’t help myself.