First of all, if you exclusively breast fed to your baby, then there will be lactational amenorrhea
for first 6 months. Otherwise heavy period in this time is required to investigate properly.
Do one ultrasound
scan and some hormone test to rule out underlying causes if any. This may be due to hormonal imbalance, stress/ anxiety or thyroid disorder
, uterine pathology etc. Consult with your doctor for suggestive measures.
Avoid stress,take healthy diet with iron supplements
, control body wt, need some hemostatic agents or hormonal medication and maintain genital hygiene properly.