PCOS gone after pregnancy??

I was diagnosed with PCOS in October 2015 while TTC. I had gotten periods before I went on the pill (around 19 years old), and I think it was mainly for regulation of my periods - cramps were horrible, flow was heavy, blah! Fast forward 10 years when I come off the pill and I had nothing. I knew in my gut something was wrong so I visited an infertility doctor who said I wasn’t ovulating and diagnosed me with PCOS. The doctors said I shouldn’t have had monthly cycles when I was younger. I needed to have medically-induced periods to start a cycle for the infertility meds. We conceived my son in February 2016. Now almost two years since our conception date, I woke up with a period yesterday! I’m still breastfeeding, and with my PCOS, I didn’t think this was possible. Has this happened to anyone else? Could my pregnancy have caused my body to reset and now my PCOS is gone??