In the beginning - I got about 2.5 ounces per side. By month 4 - I was getting under an ounce each side. I exclusively breastfed my child without any supply issues while on depo and working full time - college part time (by month 5 I had a job where she came with me) until she was around 9 months, when she finally started solids. She continued to nurse until she self weaned at 4.5 years.
Pumping is NOT the way to gauge or estimate your milk supply... the pump barely can get 25% out of your breasts while the baby's suckling easily gets 100% out every time with a good latch.
Pumping isn't easy... at least not for most Mommies. To help with pumping, maybe have your child START the let down, move him to the other breast and pump the first side he started on while he's nursing. That may help you get more.