My dd wasn't able to go longer than 2.5-3 hours between her feeds till she was almost 5 months old. It depends very much on a baby and also on mom's breast capacity. It has nothing to do, though, with a size of your breast. Almost all women (I think only 1 percent of women are truly unable to breastfeed, contrary to what most of us think) produce an adequate amount of milk for their little one but some produce less at a time of a feeding and thus baby needs to feed more often. But, within a 24 hour period each baby gets a similar amount of breastmilk in total.
Hang in there, the time flies and soon you will notice that he is able to go longer between his feeds.