Hello, Thanks for sharing your health concern with us. In the current scenario, the most likely cause for the abnormal menstrual pattern seems to be hormone imbalance. Pregnancy is a remote possibility as you have been sterilized. If it has been sometime after the surgery, I would ask you to go for a complete clinical evaluation along with hormone assays, sonogram of the pelvis preferably in the trans-vaginal route to know the status of the pelvic organs and plan further management. Management of diet and weight are also necessary. Infections have to be checked and treated. Hope your query has been clarified. Take care.