need advice only getting 1 oz pumping

Erin
Hello all,
I have 6 month old twins and I have had to pump since they were born. I had retained placenta they didn't discover till 6 weeks postpartum so I was in the hospital a lot with infections and on antibiotics that I had to pump and dump for. After six weeks of not breastfeeding them it was hard to get them back on the boob but I did. I would feed them for hours and they were still hungry. So my doctor said at there two month well baby visit they needed to be supplemented. So now fast forward to now I have been back to work for three months and I pump 3-4 times a day an I only get maybe two oz if I'm lucky for the whole day. I feel so defeated. I drink roughly 1-2 liters a day and have tried mothers milk and feuckgweed(sp) but nothing no improvements. I went to my doc and he say it could be for an iron deficiency and that de doesn't believe in giving meds I'm sooo desperate. Please if you have any advice or wisdom help me!!!!I