Maybe he's nervous. I know I was when I was first with my girlfriend. I personally think that a relationship is more likely to last if you take things slow at the start and wait until you are both completely ready. That's what was the case with me and my girlfriend and we've been together for over four years now (I'm nearly 18). It would have been closer to five years but in a fit of immature nervousness I broke up with her for a month or two.
I don't think you should force him into anything that he's not going to feel comfortable doing. Not all guys are like the loud, brash, confident, sex-mad stereotypes that we're made out to be.
I think the best thing for you to do, if you're that worried about it, is to talk to him about it. Only he is going to be able to tell you about these things. If you're close enough to be wanting some naughty relations then you're close enough to talk about these things. If you don't feel that you can talk to him about it then perhaps you're moving a little bit fast and your relationship isn't quite at the right stage yet.
Out of interest, how old are you and roughly how long have you been with each other (as an item).