Hi there - I've been recommended by many Chinese acupuncturist/herbalist that to help increase breastmilk, you should drink peanut milk. It has something to do with the proteins in peanuts that speeds production of your milk. You can get peanut milk in many asian grocery stores or peanut butter might do the trick.
I haven't tried it only because peanuts are a known allergen on my side of the family.
I mean, it doesn't hurt to try since peanuts have a lot of needed proteins anyway, right?