My little man was born 9lb 8oz and 52 cm long so he wasn't so little. He was born with a bigger than average head too - in my ultrasounds I was told it was bigger than average - that scared me so much before he was born, bit I guess a few cm doesn't make that much of a difference in the end huh?! Plus his head didn't look oversized - thank god!
He is now 10 and a 1/2 months and about 11.5kg and I am not sure how tall, haven't measured for a little while.
He didn't grow too much at the start either, sort of had to catch up with his heavy birth weight. But once he did catch up he overtook again and he's now only 3kg's lighter than my 3 year old DD... lol.
Bayden will catch up and before you know it he'll be walking, it's so sad. Enjoy him while he's little cos it just flies.