So tired.

My 9.5 week old still wakes up just about every two hours to eat. I breastfeed and formula feed and no matter which I try, he still doesn't sleep longer. He weighs over 13 lb and the pediatrician said he is fine to sleep through the night since he's gaining weight just fine. The problem is he doesn't sleep! Even during the day, he'll take a catnap for about 15 min here and there, but that's about it. How is this tiny human not exhausted?! I sure am.