8 weeks 4 days ultrasound showing different help?!

So yesterday I went to have a ultrasound done. And basically from my last period which was April the 4th. ( inserts dates below ), after my encounter with boyfriend on April 21st & 22nd

I had gotten my first positive on May 10th . Why is my baby measuring small / 2 weeks behind I have a follow up appointment next Wednesday ? Tell me guys what do you think . I was originally due Jan 9th 2021 but now their saying Jan 25th 2021 ...

How far does the baby actually look and did I ovulate later than thought?

Also I saw the baby heartbeat on May 26th at 110bpm.