My scan today at 10weeks 2 days showed a gestational sack normal for 6 weeks gestation. I tested my BFP just over 3 weeks so I am not holding out any hope. I went because I had been passing blood on wiping. The sonographer also said there were spots of blood withing the sac but this is seen often and can go on to be a viable pregnancy.
He chatted honestly with me and when I told him how early I tested positive we agreed I should plan for the worse, so I am.

I just can't fathom there being a 4 week difference, 2 weeks I can understand but not 4 weeks.

So it's off for blood tests and another US in a week if nothing naturally happens before them.