Hi. Thanks for asking in Healthcare Magic. The return of menstruation after a progesterone injection like Depo Provera is usually delayed. The cycles take many months to normalize and sometimes there may be complete suppression of periods. The increase of weight in the abdominal area is due to bulky uterus. Normally during period, the endometrial cells of uterus proliferate (multiply) resulting in thickening of endometrium (inner lining of uterus) due to the action of estrogen. When menstruation starts this endometrium is shed out as clots and the uterus reverts back to the normal size. Since you have not got the periods, the thickened endometrium has resulted in bulky uterus. Also the hormonal imbalance due to absent period has added to your problem of weight gain. An ultrasound of uterus will reveal the size of uterus and the the endometrial thickening. Since endometrial proliferation can be either simple or can result in problems like cancer, you should visit a gynecologist for a proper evaluation and to rule out problems like cancer. I hope this is useful.