I was not a big pumper, but I did experience a drop in my supply around 4 months. Here's what helped me.
Water, water, water. Lots and lots of fluids. I drank 100+oz a day. Get a good water bottle and drink, drink, drink.
Before I started taking supplements, I ate a bowl of oatmeal daily or at least a granola bar or cookie with oatmeal. My LC recommended sweet potatoes and even okra (yes, sounds strange, but okra is common in these parts). I ate snacks high in protein and never missed a meal.
I took "More Mill Plus" by Motherlove. It's a mix of Fenugreek and other milk boosting herbs. It's a little pricey and can upset your stomach, but I did see a small increase after 5-6 days (taking the recommended dosage). I found it at Whole Foods. Once I ran out of MMP, I bought plain fenugreek (GNC). Also, I found "Mother's Milk Tea" - an herbal tea - at SuperTarget (made by Modern Medicinals). It's not the best tasting, but it was a fluid!