Personally, I love using the pill to regulate my periods. I never had a normal one on my own....the doctors have no idea why, but because I have no weight gain, no excess hair, nothing on my ovaries, and all normal hormone levels, they think it must be some sort of minute hormone release that is faulty and is not allowing me to ovulate. I've been taking the pill since I was 16 (I'm 24 now) and love being able to predict and alter when I have periods. I have had three separate doctors (two gynos and a reproductive endocrinologist) tell me this is the right course for ME.
However, the pill and the PCOS are obviously effecting your body in a severe way. Kudos to you for the way you lost so much weight....that is so impressive and is truly something to be lauded for!! I would consult specialists, if possible, and see why your body is responding in this way. Maybe birth control is NOT the right option for you, but there may be other treatments out there. Do your homework and talk to as many people as possible....but be careful! This is nothing to take lightly. Best wishes.