Well i got diagnosed with PCOS when i was 17 sadly not in time to catch all the symptoms ive got , but birth control does help and if it has caused major weight gain get your sugar levels tested as you might have to take metformin to balance things out a bit. PCOS im pretty sure is hormonal imbalance which can cause problems , from weight gain, excess hair, irregular, heavy periods and can cause obviously cysts and can make you infertile or hard to fall pregnant
Pcos is no big deal but you must take care of it. Birth control will force your body to have periods. Not taking care of pcos will make it difficult to conceive children .