Baby's weight?

Kara

I may sound totally stupid, I'm a FTM. My son is 7 months old and 19 pounds, 28in. He's not exactly chubby but has a teeny belly ha. His dad is also very tall so he long. When does their weight gain start slowing down? I'm concerned that if he's 19 pounds now he'll be like 40 pounds when he's 1. He just had a checkup and his dr said he's growing perfectly. So he's healthy, but I'm just curious.