I like this girl but?

Everyone in this story is 17 btw so were all old enough to have sex etc. So basically I met this girl when I moved to my new school at the start of the year. She's a good friend of mine.About two months ago one of my friends had a camping party. I was allowed to invite my best friend from my old school. Him and my female friend ended up doing 'sexual' things' in a tent but not actually having sex. They don't talk now as they live far apart & he isn't really interested in her. So last friday we were all at a party (my old friend wasn't there) and me and the girl in question went upstairs and we basically hooked up. Now my friends are telling me they think she likes me even my old friend admitted when he was with her he felt that she was settling for second best because she couldn't have me :S Now I've thought about it I can think of lots of times where she's flirted with me but I missed it. My dilemma is what do I do now? I like her and I could see myself happy with her, but how can I be sure I'm not reading too much into it? She's not a slag and only hooks up with guys she likes, and then there's the looming prospect of my old friend.What do I do?