I never had any problems nursing my bio son. However, pumping was another issue. Even when he was less than a year (so taking LOTS of milk) I was lucky to get 2 ounces during 30 to 40 minutes of pumping. (Pump 7 minutes, take a break, pump 7 minutes with another possible break and pump.) He was exclusively breastfed and other mothers could get a dozen ounces in that same time period. Not me. So, don't let your pumping results bother you. Be aware your baby may need supplementation, but once you have baby at breast, maybe they won't.
Good Luck.