well when my son was a month old according sa pedia nya wag muna mag-vits.'pag 3mos na lang daw. my baby is pretty much the same as your description.. hindi sya bilog at hindi sya payat.. malaman sya and weighs minimal above than normal..according sa pedia mas gusto nila ang mga batang sakto lang kasi we may not even know yung mga bilugan eh obese na pala🙂