I went for my u/s last week. I too going by my last period should have been about 8 weeks but by the scan, I seen the sac only and measured at 5w2d. My bloods also indicated around 6 weeks. So my GP is sending me again in two weeks. I'm not to worried as my last daughter , with my first u/s I didnt see anything no sac nothing but two weeks after I seen her hb. And she is now a very happy two year old.