I would wait a few days and see what happens. If you don't get it, you may want to call your doctor. Depending on the type of pill you are on, your cycle is hard to regulate after childbirth, especially when you are nursing.
PS The pill and the minipill can affect your supply. If you continue to have supply problems, you may consider going off the pills and using an alternative form of non-hormonal ABC, like condoms. :wink: