Isn't he a little young to level off already?

Lake had his first doctor's appointment today. We made it strickly to start him a file at our clinic. He was a super fantastic trooper the whole time especially since he didn't really nap all morning due to 3 4-year olds running amuck (or so I hear - sometimes it's good to be the working one!) His head is now 41 around (again a big YIKES!), he's almost 25 inches long and a little shocking here, he only weighs 15.11 lbs. A little shocking since he hasn't put on a full pound from his last weigh in and typically at his age he should be putting on 1-2 pounds a month. The Dr. was a little concerned but we're all taking it with a grain of salt as he has reached all the 3 month milestones already - and clearly, take one good look at him and you know that boy is NOT starving! The Dr. did ask for us to have him weighed again within the next 2 weeks just to be sure. No biggie to us, but still I kinda have to wonder. When I'm leaving for work, Lake is either sleeping off his 2nd breakfast or having his 2nd breakfast. When I come home from work, he is looking for his bed time snack or waking up from his 2 full feeds at dinner. So if he is eating all that (and a bag of chips) than where is it going?