i m dr. ghazi
what is your age?
how old is your son?
is he still feeds mothers milk?
these are few questions needed to be answered before getting an advice
in general there is lactational amenorrhoea (no mensturation when a female is feeding her milk to the infant particularly within 6 month - after delivary)
if you youngest child is of 2yrs or more and u are on pills u need to get an hormonal
assay and consult gynecologist