Should I Stay With Him?

I've known my boyfriend since we were 13, and now I'm 16 and he's 17 and we've been steadily dating for about 8 months. We've talked more than once about the possibility of getting married, having kids, etc., but there's one thing I'm kind of concerned about. It's not that I don't love him. I really love him a lot. He's one of those one-in-a-million teenage boys that isn't a total perv. He's really sweet to me, and he's just a really nice, solid guy. The problem is, well, that I'm 16 and he's 17. I know that's really young to get married, though, so what I really want to do is sort of take a break from the relationship and date other people, just so that I can really know for sure that he's the one. Then maybe get back together with him in a few months, years, whatever. I know he's worried that if we break up than he won't be able to find another girlfriend, but he's my first boyfriend and I'm his first girlfriend. How can I tell him this the right way?