Based on your MCHN's theory, I should reduce BFs to my 6mo as he's light years off the charts for his weight (and length)!!! My little fella is closer to the size of a 12-14 month old. He's just an all round big boy who gets one small meal a day and is otherwise fully BFd. OK, so we're not talking about a BFd bub, but my point stands that some bubs are - quite normally - larger than others. As has been mentioned, if your DS is having healthy meals and isn't eating non-stop from sun-up to sun-down I wouldn't be at all concerned by what the MCHN said.