Wrong dates?

So I tought I'm 7+1 weeks but today at the early scan I found out I'm 4+3 and only the gestational sac and yolk sac was visible. I have to repeat the scan in 2 weeks to check how things are progressing. I'm still brestfeeding my 8 months old and my cycle was very irregular, maybe I had a late ovulation? If I'm only 4+3 and I've had my first pregnancy test 2 weeks ago, that means the conception date was just a few days before I took the test? Just soo confused and worried... 😔Did someone else experienced this?