Not all women can respond to the pump. Some women have no problems at all. What you are trying to do with a pump is to fool your body to think that the baby is nursing. That is another reason for the better pumps out there. They are made to most mimic the baby s sucking so that you can have a letdown thus be able to pump more milk.
Letdowns are very important in pumping.
It is normal to be able to get 1 to 2 ounces of milk at each pump session. It is also normal to be able to get 11 to 12 ounces of milk at each session. Every woman is different and it all depends on the circumstances around your pump session. Such as your schedule, level of relaxation, having a letdown, day of the week and the time of day You can generally pump more on a Monday than you can on a Friday. You also pump more ounces in the morning than you do in the afternoon or evening.