The more you pump/feed the more yout body will make. But like one of the above said lots of fluids and you have to eat. After my last pregnancy I caught myself skipping meals to lose weight and I was bf. I noticed my supply was going down due to my low calorie intake.
I have a recipie for cookies that supposodly help with supply somewhere on my pinterest. You could probably google it. A stout beer is supposed to help, along with what the other ladies posted. And definitly water, I would drink more then the 8 glasses a day.
Make sure your drinking at least Eight 8oz glasses of water a day. After you breastfeed drink a crap ton of water each time. Pump even after baby is done nursing and feed more often. I wake my son up every two hours change his diaper and offer him a boob. I was running low as well and haven't tried teas or pills yet. I looked up things I could do and eat and found that adequate water and oatmeal helps. Its helped within 24hrs. If it gets low again I will be looking to get the other supplements.
Traditional Medicinals brand has a Mothers Milk tea that is awesome.
Fenegreek tea. I'm not sure if that's the right spelling though.
Increase demand; try hand expression or pumping. Of course, stay hydrated.