PCOS is not usually associated w/ an enlarged pituitary -- would recommend consultation with a general endocrinologist (or pituitary specialist) to see if there is anything else to consider.
I was also diagnosised with PCO and a pituitary small tumor - - - I went on Parlodel two years ago - (originally I was on 2.5mg twice a day, now I only need 1.25 mg every other day). It regulated my cycles within 2 months and helped with other PCO symptoms. I did acheive pregnancies with an infertility specialist but they all ended in miscarriage. I've only had one MRI 10 years ago and then I had follow up with an endocron. originally 2x a year now its just annual. I have not had any concerns or huge side effects with this diagnosis and found it easy to manage. We adopted three kids when the pregnancies continued to fail. good luck