PCOS, First Time Mom, and Missed Period

So I'm 2 months postpartum with my first baby. I have PCOS and had to be put on Metformin in order to release an egg and get pregnant after non-stop unprotected sex failed on its own. I had my first period since giving birth on January 22. My period was due yesterday and the last two days I had some dull cramping and nothing else. Before my pregnancy I was 30 pounds lighter and had regular periods to the day. When I was heavier (like now) I was a little irregular. SO. I'm worried I may be pregnant. We use condoms, but there was a day or two where we just did the whole "pull out" method. Does anyone have experience where it's normal to miss a period postpartum and does it take a while to regulate? I am pumping, but not breastfeeding as I'm only producing an ounce or two a day.