Do what you feel is right for you. You cant let so called friends live your life for you, this "friend" of yours sounds like a control freak. Only you can judge what is right for you, just be careful and to avoid unwnated pregnancies or STDs. So be your own person, make your own decisions.
Ultimitely, it is your choice, but fifteen is pretty young. As a guy, I can tell you that I didn't have intercourse until I was almost 18 and I did do it with a girl I was very much in love with. You don't have to have intercourse to enjoy your sexual side. Just think about that, okay? And good luck.
For a fifteen year old, you display a lot of wisdom. Always remember, you have one life, enjoy it. But don't risk your future by getting pregnate or with an STD. Sex is great, but it's not the only thing. I think you understand this. You are a very smart girl.
I say, you're ready for sex when you're ready for the consequences. Can you make a good decision about the baby? Can you receive treatment if you contract a disease? Will you be able to finish high school and go to college? Will this boy respect you after the deed? If the answer to ANY of those questions is no, then wait.
Keep going. If it feels good, do it!!!