Maybe a stupid question about conception...

asibilrud

I have always had the most erratic periods, like I'm talking every 2-3 months I would get one. Therefore when I found out i was pregnant, I had NO idea when i conceived. It doesn't matter much, I am generally just wondering. I received my first ultrasound at 8 weeks 6 days and was given an EDD of March 13. According to a reverse conception chart, that measn I might have conceived on June 20th, but my last period was May 4th

I always measure right on time (which I know isn't too accurate) but my question is: if I have this baby before my EDD could that mean I conceived that much sooner? or not neccesarily?