Honey, my husband and I knew within a few days after we met. That was almost 21 years ago (we've been married for 18 of 'em).
If he doesn't know now, when will he? When you're older and it's tougher to have and raise children? When the relationship gets stale? When it gets somehow, magically, fresher?
I think either this guy does not want to get married at all (not everyone wants to) or he is dickering around or he really is this indecisive. And, well, sometimes you need to stop being Hamlet and just make up your mind once in a while. I mean, is he gonna name your kids when they're in Middle School?
I know you love him, but right now, from my perspective, this is looking like just one big, fat time sink. I would tell him to hit the bricks but that's me. You should ask him, what will it take? And be prepared if it's not an answer you want to hear. And, by the way, "more time" is not an answer. He's had plenty. Time to poop or get off the pot.