Pumping is NOT an indicator of how much milk your breasts produce - I have two sisters who were never able to pump more than an ounce or two, and they were able to feed four babies just fine between the two of them.
When they're really little, you go on the fact that they are peeing and pooping consistently, if they're sastified (i.e. sleeping/"milk coma" afterwards) and if they're gaining weight.
Supply and demand are your friend, so if you're worried, offer the breast more, and drink tons of water to just help things along. hth!
DS2 - Oct 2010 (my VBAC baby!)
To determine if I had a supply problem, my LC weighed DS before I nursed and then immediately afterward. The difference in weight was the amount he took in (which for me was an abysmal amount). I thought I was having a problem to start with because DS was not gaining enough weight and was never satisfied after a feeding.
We were out of state for weeks 2-6, and I didnt know I had a supply problem until I finally found a place to weigh her at week 4, and found out she was not up to birth weight. Thinking back, there may have been signs, but being a first time mom, I missed them. (My supply went down because she didn't suck properly, although I thought the first surgery at 1 week 6 days fixed it).