Natural ovulation w/PCOS

Th

I was just diagnosed with PCOS. My dr. Performed an ultrasound on me and I clearly can see all the little cysts. We also clearly could see a dominate follicle of 15mm. My projected ovulation date is 4 days after having that ultrasound done and my dr said they grow 1mm-2mm a day so there is a chance I produce a healthy size follicle for ovulation. My question is, how can I have PCOS but still ovulate monthly? I have a normal, 34 day cycle where I do ovulate monthly. I’m just so confused. Anyone have the same issue? She put me on 500mg of metfomin.