Hi

My baby is also small. He was born 3.5 weeks early and weighed 5lb 15oz or 2716g.
Our Paed has told us that it takes time for little premmie bubs to catch up.
He also told us that he may not be huge as I'm quite small even though hubby is bigger.
My son is 7 months and weighs 6.4 kgs now.

If you are worried I'd suggest talking to your dr or health nurse and see what they say