In my experience it is difficult to over-feed a baby. My two are very opinionated and if they don't want something they will firmly clamp their mouths shut! At least for the moment I would follow your babies lead and simply feed her until she loses interest/stops opening her mouth. Also, have you introduced finger foods yet as that is the point where the baby really does decide how much they want to go in (or on the floor!). As the previous poster said, just try to keep the food as healthy as possible and it should be fine. Some babies are just big. My daughter was pretty chubby up until about 14mths as she not only ate lots but also consumed alot of milk and as soon as she was walking and running she slimmed down really quickly. Good luck!