question about due date stuff

Okay my first ultrasound I was 7 weeks 2 days and baby measured exactly that but I think the doctor accidentally measured some of the yolk sac too because baby partially rested on it. I went back at 9 weeks 2 days and baby measured 9 weeks exactly, with a strong heartbeat of 164, is that normal? So now I'm 9 weeks 6 days, would I be 9 weeks 4 days or still 9 weeks 6 days?