Without knowing his age, I would guess he's between 3-4 months? That is the prime age for quick feeds, distracted feeds, and fussy feeding. You could try stretching out the length between feeds by 15 min or so to see if he is hungrier, he'll eat better. As long as he's getting 5-7 bfs per day (at 3-4 months), happy and sleeping well, he's probably getting enough.