I had a scan yesterday and from external scan she could only see sac but couldn't see what was inside it cause it was so small and certainly no heartbeat from external. I started to cry but then she did internal scan and there was a tiny baby with a heartbeat and yolk sac. It could have just been far too early for external scan for you and maybe you are a bit behind with dates. I should have been 7+1 according to first day of last period but only measured 6+4 cause I ovulated a few days late.
She said I could have internal scan everytime I go if I like cause she said it's a lot easier and clearer esp leading up to 12 weeks.
I will definatley be having internal next time to save the worry that an external one can cause.
Fingers crossed for you that everything is ok at next scan, maybe ask for internal one too.
x