Hayley, you can't overfeed them - if they are full they wont drink it simple as that, so if she is taking it, she must need it. How long is she? that can make a difference to how they look to, as with a longer baby the weight is distrubuted over their length, making them look leaner, and obviously a shorter bub will look chubbier. You have nothing to worry about, some babies are just chubby, and they all even out once they are toddlers anyway and they are mobile.