If, however, he is snacking for a few minutes constantly through the day, that can be a burden. If he is not emptying your breasts at each feeding, he is getting the early milk but not the richer "hind" milk. One trick is to pump your breast before feeding him so that he gets more of that later milk. This might satisfy him so that he goes longer between feeds, and may even nurse longer at a feeding.
Nursing from only one breast at each feeding is not uncommon and not a problem as long as you alternate sides from feeding to feeding. You may be more comfortable if you express some milk from the unused side to relieve your engorgement. Some infants have a definite preference for one breast over the other, leading me to believe that sometimes one is chocolate and one vanilla.
Finally, he may be due for a growth spurt about now, and will start to nurse longer and/or from both breasts when that happens.