Wait... don't *make* him break up with you over this
Unless you're looking to be his wife, you shouldn't really concern yourself with, "I worry that he won't love me as much as he could", or anything similar. Love is all about learning experiences, and sometimes we've all gotta start somewhere. If he wants to stay with you, and if you like him, be careful not to worry too much.
Because if he doesn't know if he loves you, there's no guarantee at all that he'd know if he loved someone else if he found her. None. Maybe he just needs (and wants) more time with you, because he thinks you could be the first one he really fell for.
Give it time... ^^;
HOWEVER, I do suggest resolving the "hes not one to share emotions" problem. >_> It only makes things like this far more complex than they need to be.. Confront him about it, ask him more questions, be relentless if you must, to be reassured or answered with whatever concerns you have for him.