2 month check up

went in for our 2 month check up today and our ped was a little worried about his weight gain. he's already doubled his weight and apparently babies usually don't reach this point until about 4 months. she said not to do anything different at this point but to be aware of it. he was 6.13 when he was born, dropped down to 6.7 at 4 days, back up to 7.4 at 2 weeks, then at a month he was 10.2 and now is 13 lbs at 2 months. how has everyone else's baby's weight gain been? he's ebf.