10 weeks exactly?

I went to the doctor on 11/23 and they weren't sure how far along I am because of irregular periods. They did a vaginal ultrasound and could only see the gestational sac. I went back today 12/3 and I was thinking I was 6 weeks 1 day. They did another vaginal ultrasound and it measured at 10 weeks. I could see the baby wiggling around and the heartbeat flicker. Could also hear the heartbeat. They said they are not sure why they couldn't see much last time. Maybe because I am overweight and I had a full bladder. I am not sure if I am 10 weeks because you can still see the yolk sac.