I had my baby almost 3 weeks ago, and I'm breastfeeding. Last week, I was producing so much milk that I needed to pump every few hours, even after feeding her, just to be comfortable. I'd produce more than 5oz in one sitting. Well now, I'm lucky to get an ounce in total. What can I do to keep my milk supply up? I'd really rather not have to switch over to formula if I can prevent it.