my third baby having 65days old fch .birth wt 3.200 mg.but now weight is 3.800 gmsand baby look too tiny.is this normal?

A. hello baby gaining a minimum of 600 gram to 800 gram per month then it is a good weight gain and absolutely nothing to worry about otherwise it would be better to check with your doctor and also if the breast milk is not sufficient you can give infant formula milk using a b p a free bottle like babyhug