Infants for sure need lots of sleep, but its not usually all in one big long stretch. As long as weight gain is OK it's not a big problem as far as I can see, and as long as your baby will take the breast when offered then it should be easy to fit in more nursing sessions during the day. but if you would like to encourage more napping,- Are you be any chance trying avoid nursing baby to sleep? Nursing is typically a sure fire way to gentle a baby into sleep for naps or nighttime. If you have time/inclination to lay down with baby and nap together so much the better. Also walking baby down in a sling, car rides, stroller rides, etc. all worked well for me. But my kids had no particular problems napping. Nap times & lenghts certainly did transistion and change, but at this age I do not recall there being any particular pattern. Basically when they were tired, they napped as long as I set the stage, so to speak.
Is this normal for a baby to sleep this much? He fights naps. Should I wake him up to eat? Obviously he has no weight gain issues.