As long as things are developing normally I wouldn't worry. I am not good figuring these things out...lol!! The only way i knew mine was because it was FET and there are exact dates. Wait for your beta and go from there. Last time i was pregnant everywhere i went had different ways of figuirng out how far along you were. The fertility clinic, 2 different u/s locationsa nd my regular doctor! Some little embies take longer to develop. I have a friend on here that she figured she was 6 weeks and there was no HB and she was terrified...she went again 2 weeks later and all was good. She even had IUI and turns out she was like 3 days behind what she thought. And even 1 day this early on can make a world of difference in development...soooo....try to stay positive!