It is somewhat unusual for a baby to not start on drinking other things by this time, but some babies are more attached than others, and he will grow out of it. Breastfeeding can delay normal cycles, so it shouldn't be of too much concern, unless you are feeling out of sorts in other ways physically.It may also be a sign that your body needs more nutrition, rest, and a break from having more kids just now. You can cut down on the feedings to twice a day for awhile, then maybe a little less after a while, and see if that takes. If you are concerned with it, then consult with your doctor and your La Leche League Leader in your area. If you are not hooked up with that organization, I'd highly recommend them! Congrats on your successful bond with your son.