I would like to know what tablet u have taken for your periods that has caused weight gain.
For periods to become regular in polycystic ovaries, you may need to take the medications regularly for 12-18 months, along with healthy lifestyle & regular exercise. Because weight gain can be associated with polycystic ovaries, which together can cause irregular menstural cycle & other metabolic abnormalities.
I would suggest pls visit an Endocrinologist & take opinion, polycystic condition is treatable. Thanks.