Hi there! My ds just turned 3 months on Thursday (2 days ago) and he weighs in at 17 lbs 5 ozs!!! At 2 months he was 15lbs 4ozs. He was 9lbs 15.8ozs at birth. It seems our little guys are on the same track! I b/f Tanner and my Doc always jokes with me that it's more like cream!
He is wearing size 2 diapers, almost 3 and fits into 6 to 12 month size clothing. I love him being so big!

He is so strong and has been hitting milestones much sooner than my first did. While he was big at birth as well
(9lbs 6ozs) he didn't grow as quickly in infanthood.
Don't worry about it! Tanner is in the 110th percentile for weight and height. He is over 25 inches long now and was 21.2 inches at birth.
Just so you know, my dh is only 5' 9" and very slender. I am only 5'3" and small boned as well. My usual weight is about 110 to 115 lbs. I don't have a clue how we had such big babies but I love it!
DS#1 is only 25 lbs now soaking wet and still fits in some 12 to 18 month stuff and he is 25 months old! He is a little guy now!
Your son will slow down for sure, especially once he starts crawling and walking! Enjoy his baby pudge now because before you know it it'll be gone!