The first time thing..

My boyfriend and I have made out and got really horny 30+ times. He isn't a virgin, but I am. He says he will wait as long as I need before having sex. I really want to have sex with him, and we almost have. We got to the start taking off clothing part a couple of times. I just get nervous and then say "we can't".

I always feel like I am going to so something wrong. Or like I'm not going to full fill his needs. Or I won't be any good. How do I make it so that I will, full fill him; be good; and not do anything wrong? How do I not be so scared? I really want to have sex with him. I just scared. I have never been so comfortable with anyone before. We do everything together, Everyday. Its just the sex part, that scares me a little..... Does anyone know anything that would help me out a little?