There is some research out there that says that a child who is fed cereal before 6 months has the increased chance of getting adult onset diabetes in later life. Don't let this scare you, for your child is out of danger. The Amer. Academy of Pediatrics recommended in 1998 that mother's nurse for a year, and not to supplement with any other food before 6 months.
If you are needing to increase your milk supply, there are a few suggestions.
From the book, PRESCRIPTION FOR NUTRITIONAL HEALING, a book every household should have, in my humble opinion: Drink more water and fluids, In some studies, when one consumes garlic, it increases the baby's desire for milk and nursed longer. This makes sense to me, if you know anything about the feedback mechanisms in the body for nursing; the more a child nurses, the more milk you will create. Drink raspberry tea (the leafs, but I think the fruit will do as well), and Anise; they both promote milk production. Avoid eating sage, black walnet and yarrow, which reduce milk production. But those herbs will be nice to use when you wean.
Anise, I like the taste of anise. At the World Market, I find those little tins of Anise candies from France, at the back of the Lawrence store. I am sure any anise will do tho.