Who brings up the topic of sex in a relationship?

The topic of sex usually isn't discussed until you have been doing it for a period of time. In general things like that just happen when the moment is right. If your snuggling and making out hasn't led to sex yet just give it time. If you bring it up she may freak out. "I was wondering when you were going to want to have sex with me." is a little blunt. If you still want to bring it up make it subtle. Start with some foreplay if she is uncomfortable going all the way.

so I take it you and your girlfriend got back together then? don't think sex is the best thing to bring up if you just got back together

At your ages, you really shouldn't be having sex at all.

I realize there's peer pressure, but peer pressure goes away in time.

What's the rush? If tomorrow never comes, because the world ended, what difference will it make that you had sex? And if there's a tomorrow, there'll be time to have sex when you're both older and more certain you're going to stay together.

Kudos to your girlfriend for still being a virgin at 16, as I think that's pretty rare these days.

Parents are too uninvolved in their children's sex lives, generally letting them learn it all the wrong way - from their peers. Your peers likely know just as little or as much about it as you do. There are adults in their 30s, and older who think sex is all about intercourse, which shows how much they know. Sex isn't supposed to be a recreational activity, and young people all too often treat it as such.

When to talk about the subject is now. Find out how each of you feel about it, but don't do it just because you think you're in love, or because you're trying to do what your peers say they're doing. How do you really know what your peers are doing, unless you're there actually watching them do it? Like I said, sex has become a recreational activity among people just for the sake of doing it.