Hi,
Welcome to ehealthforum,
If you are diagnosed with PCOS, then consider discussing with your treating doctor/gynecologist about getting started on treatment with insulin modifiers to help with reversing the PCOS changes (as most common cause for PCOS is insulin resistance). Oral contraceptive pills only help to regulate the period cycles, not correct the PCOS.
Focus on determining the exact cause for the irregular periods and get started on appropriate treatment for correction and regulation of periods.
Take care.