Why do you think you are only producing 3 oz / day?
Tonya gave good info. Milk production is supply and demand, so if you start to consistenly demand milk again, your body should increase the supply. As she mentioned, the boosters will not work without the increase in demand for milk.
The 'power pumping' or nusing as she mentioned is going to be your best way to tell your body to make more milk. Good luck!