If your boyfriend cannot respect that fact that you are unsure and want to wait, then you need to kick his butt to the curb. You should never (at any time) feel pressured to have sex, especially if you are still a virgin.
From a boy's point of view (and a biological point of view) waldorff is pretty much on the mark. However, it isn't a boy asking this question, it's you.
So know this: ALL boys ALWAYS want sex. Most will attempt to seduce you by any means available including emotional blackmail. (That's what VirginiaL was talking about when she said, "If you loved me you do it.")
Only you can decide whether you really want to do it or not but, since you're still a virgin, for heaven's sake get sound advice from a RESPONSIBLE adult -- preferably your mother. Even if she doesn't approve of you having sex she'll be even more concerned about an unwanted baby ruining your life -- and hers.
It may be unfashionable to say NO these days, but it's still your choice. Stick to your guns. There are still plenty of boys out there who will respect your decision.