Off by 2 weeks

n/
Hey girls. Just wanted to see if anyone else has experienced this and could maybe offer me a little reassurance as I'm kind of a nervous wreck right now. According to my LMP I should be 7 weeks 2 days. My periods have been somewhat irregular and my doctor suspected I ovulated late. I had implantation bleeding the 15th and a positive pregnancy test the 17th. I assumed I was maybe a week behind but today at the scan the sac only measured 5 weeks 3 days. She was able to see a yolk sac which I think is a good sign. Wondering if anyone could offer some clarity on these dates and if it would make sense. It would have made me 3 weeks when I got my positive. I'm praying the baby hasn't stopped developing and I'm just earlier than I thought. Any responses are greatly appreciated. Due for another scan in 10 days.