No period! Help! "I'm not pregnant"

So i had my son about 3 months ago. I had my period at 8 weeks postpartum which only lasted a little less than a week. My son turns 4 months on the 20th of this month. I haven't gotten a "regular" period yet. I have pcos but I've never missed more than a month so I'm confused. I googled that women who exclusively breast feed sometimes get lighter periods or no periods at all but I only pump, and it's not much daily either. Would pumping be the same as exclusively breast feeding? Has this happened to anyone else