A good cup of strong fennel tea will promote the production of milk. It is a great time in your life to experiment with herbal teas as they provide an abundance of phyto-nutirents and minerals that will fortify your milk.
Stick to common herbs like mint, chamomile, fennel, green tea, and some of the mixes made by celestial seasons or similar companies. Avoid herbs that may have a hormonal or detox influence. This is not a good time for you to do a detox as many toxins will leave via breast milk.