Birth control!

So I had my baby on July 27th and I started birth control a while ago I just started a new back today this will be my second pack. I take 3 weeks pill then 1 weeks sugar pills. My first pack i abstained from sex and haven’t at all actually had sexsince i was pregnant . However today I had unprotected sex and he didn’t pull out am I safe since I’m on the pill? I’m so worried I can’t have another baby I’ve also have had irregular bleeding since birth that comes and goes frequently