I had the same issue when I was breastfeeding. If you want your breastmilk flow to increase you need to attache your baby to your breast even if you dont have a milk supply, just your baby sucking more on both of your breast throughout the day multiple times will create more of a breastmilk supply. Remember when you are breastfeeding your diet needs to be the same as if you were pregnant. Some medications can reduce breastmilk flow.
Tips
1) Use a nipple gard to see how your flow is.
2) Try not to breast pump so much, your body will get used to the pump and will start producing less.
3) Eat very healthy.
4) if your baby is asleep then he or see is full.
5) your baby will let you know if he or see is is still hungry.
6) if you still have doubts you can ask your doctor to weigh your baby, and you can see if your baby is gaining the right amount he or she should be, if they are not than you can feed them more thoughtout the day.