Journey, I doubt he's uncomfortable with who you are now; he's probably just concerned that he can't keep up with the new you, kwim? That you are too sophisticated for him or something..
My H said something like this to me last night. He was referring to his self esteem and said that he would be at the rock bottom of the barrel, were it not for my faith in him. This faith spurs him on to live up to his potential. He was talking specifically about sexual confidence and being a confident lover during sex.
His confidence is still a little shaky outside the bedroom but I felt good that he views himself positively during the actual act.
Your H will get there, J.
If he's a teenager still, then the only way to help the process along is by lots of praise and goodwill. We're all still growing and he's just bringing up the rear, while you are at the top of your game.