First time

Okay so my boyfriend and I have known each other for 6 years. We dated for a while 3 years ago, stayed friends after we broke up, and have now been dating again for a while. He's not a virgin but I am. I'm very comfortable with him and we have done stuff before but never gone all the way. I think we might tomorrow and I'm nervous, I don't want to regret it. Any advice?? (I'm 17 and I've been on birth control for three years.)