I have many arguments for leaving sex until marriage, which I'm not going to put here for the risk of being called frigid or whatever.
What I will say is that your virginity is the best possible gift to give your partner on your wedding night.
We had a "marriage day" at our school were we asked couples questions, most were old and had never slept with another partner, but the one young couple we got to talk to said they had both slept with other people before each other, and it was the hardest hurdle they had to get over and come to terms with in their relationship, and they really regretted not leaving sex until marriage.
Just something to think about.
Oh, and for the girls, I'm not speaking for everyone here, but most guys would like to marry virgins rather than girls who had slept around a lot.