My sac was perfectly fine too, the right shape and size for 6 weeks, the sonographer kept telling me everything was fine and I had just got my dates wrong, and it was just a bit early to see the foetus yet, only I knew I hadn’t got my dates wrong as I had got a positive pregnancy test 7 weeks earlier, I’m glad I was a bit more clued up otherwise the sonographer would have given me false hope, I knew in my intuition something wasn’t right as I had barely any symptoms at all, wouldn’t have even known I was pregnant if it weren’t for the test, I know not every woman gets a lot of symptoms but I just really didn’t feel pregnant at all with the blighted ovum, my next pregnancy with my baby daughter had a scan at 6 weeks, could see the fetus and heartbeat easily and had awful sickness every day, I’m not trying to scare you or say anything is wrong with your pregnancy but what I would say is keep abit of an open mind as it sounds like they are dating the pregnancy quite a bit earlier to what you thought you were and I don’t think sonographers ask enough questions either to determine whether it’s gonna be viable or not they just go off what they see on the screen but they should be asking the woman when she tested positive aswell to make sure it at least vaguely matches up, in my example they were trying to tell me everything was fine and I was 6 weeks pregnant and were just disregarding me when I was trying to tell them I couldn’t be as I had tested positive 7 weeks earlier, it annoys me now when I see that they just tell people everything is fine without really digging a bit deeper, I hope it’s all fine for you anyway they sound really positive that it’s all progressing well for you x