Is my baby eating to much?

My son is 3 weeks old and lately he has seemed to be eating a lot more than he used to. I finally got a pump so I when I go back to work I would be able to have someone watch him because I know that milk is best milk :) He seems to be eating about 5 ounces during feedings, is that to much? Even after that amount he still seems to want to eat. I don't have him on a pacifier but I'm trying because I know it's an instinct to want to suck and I figure that's what he wants to do because during nursing sometimes he just seems to be just sucking on my and not actually eating. (I don't hear swallowing vs. just sucking) So 3 questions. Is he eating to much for how old he is? Can I put a little pinch of cereal in my milk to help fill him up because he is sucking me dry and I can't seem to save up any milk if I need to go anywhere. And how can I get him on a pacifier?