Hi,
Welcome to ehealthforum.
The symptoms that you are having are due to the hormone contained in Provera (medroxyprogesterone). If your periods are heavy and not controlled by the medication, then you would need further work-up with hormonal study (FSH, LH, Prolactin, DHEA). Change in bleeding pattern and duration is indicative of hormonal problems. Visit another gynecologist (not regular doctor/GP) if needed for a second opinion on your condition, go ahead with complete evaluation.
The side effects of the Provera, if affecting your daily should be considered and alternative medication might need to be prescribed to control your symptoms and minimize the side effects.
Most common cause for PCOS is insulin resistance, hence use of insulin modifiers help in better control of symptoms. Consider discussing about use of insulin modifiers to control the PCOS changes. Once changes are under control, then ovulation inducers can be started for you to help egg release from ovaries and plan your pregnancy accordingly.
Hope this helps. Take care.