Does my daughter eat too much?

my 11 month old daughter is in size 18 month clothes already. at her 9 month check up she was 21 lbs. my son who is almost 5 only weighs forty. for breakfast she can eat a whole packet of oatmeal. for lunch she will eat a whole gerber graduate meal, or half a can of spaghettios, or half a sandwich. for dinner she has whatever we have but will have a good portion. half a of chicken, or whole hot dog, or large slice of pizza (veggie) or half pork chop. plus whatever sides we have such as potatoes and veggies. she eats more than my son sometimes. she also has a few snacks through out the day gerber cereal bar, fresh fruit, yogurt drops. things such as these. she is still on formula she has 3 to 4 six ounce bottles a day. and if someone is eating in front of her she screams until she gets something to eat too. she was born three weeks early and weighed 8 lbs 14 oz. i just don't remember my son eating this much. is this normal? should i be worried?