How accurate are scans at 6 5 weeks and 11.5 weeks?

My 6 weeks scan weren’t very clear, and my dates were right tho X

I had an early reassurance scan and calculated i was nearly 8 weeks based on my lmp.The early scan said i was 6.5 weeks there was a very tiny sac and yolk and a flickering heart beat..it would of bee more advanced at more towards 8 weeks from what I've read xx

I then went on to have my dating scan and baby was 11.5 weeks.

Ive since had 2 more scans and they are calculating baby is due on 10th August.I am 27 weeks today.

So if i ovulated late it would of set the dates back? I am a little confused about it.The scan at almost 12 weeks are very accurate though arnt they? Xxx

Yes.Been googling so much into and worrying so much.I had my period after taking it as well my lmp was 24th Oct xxx

My midwife told me scans aren't 100% untill after around 10 weeks+

Well i had one at 11.5 weeks and my 20 week scan both said my due date was August 10th xx