did your baby gain less weight when they started crawling/being more active?

my son was born weighing 6 pounds 5 ounces. he’s now 3 months and a few days, and weighs 15 pounds!! he’s gotten pretty chunky, but he’s exclusively breastfed right now and i’m not worried, but i wasn’t expecting him to gain so much lol.

when he’s more active, will he stop gaining weight so quickly? i know it’s not a problem now and he’s within normal range (he’s also pretty long/tall) but i don’t want it to be a problem in the future :)