Leslie, while I was looking for info for our foamy poop issue I came across this info here: http://www.llli.org/FAQ/oversupply.html and thought this portion might help you.

If you are uncomfortable on the breast that is not being used before you are ready to nurse on it again, you can hand express or pump for only a few moments (20-30 seconds or less), just enough to relieve some discomfort. Do not pump too much or you will signal your breasts to produce even more milk. There is a certain whey protein in the milk, called "Feedback Inhibitor of Lactation" (FIL), that begins to build up and concentrate when milk is not removed for a while. This protein needs to be allowed to build up high enough to trigger the breast to cut back milk production. By removing just barely enough milk to be comfortable, but still allowing the breast to be full enough to trigger the "cut back milk production" message, most mothers can decrease milk production without risking plugged ducts or a breast infection. Many mothers find that cold compresses -- chilled raw green cabbage leaves or a bag of frozen peas -- help ease the discomfort and reduce swelling from being overly full.