Dale-- Sounds like you are doing just fabulous for having only pumped for 3 weeks--- wow!! I have heard two different ways of estimating baby's need. The first way is simply that most newborns need between 17 and 25 ounces per day-- I would guess that more active, bigger babies would need the high end of that amount, and smaller babies would need the low end of that. The other rule of thumb I have heard is that babies need about 2-3/4 ounces per pound per day--- so by that guesstimate a 6 lb baby would need somewhere around 17 oz per day and a 9 lb baby would need more like 25 ounces.... as you can see that lines up exactly with the range suggested in the first rule of thumb, but allows you to guess more exactly IF you know the baby's weight...Hope that helps....