@TheBirdintheCave from the 1st thread I found on Mumsnet (I hope this reassures you - I didnt even look hard to find them 💕):
SunnySideUp2020 · 20/03/2021 08:10
Oh and my 5 days discrepancy at the beginning, became 3 days at 10 weeks and by 12w scan it matches my LMP which again is weird because i ovulate late in the cycle!
I am 38 weeks now :)
EmzyD · 20/03/2021 08:15
I was in a similar situation for my early scan - I thought I was 7w exactly and early scan dated me at 6+2. Had my 12 week scan yesterday and am dated as 13+1 so all caught up to where I originally thought I should be. At my early scan they warned me the dating was pretty inaccurate. Hopefully this helps!
lilymty · 21/03/2021 10:47
I was 100% sure of my dates when I went for my 6 week scan but I was only measuring 4 weeks. I'm now 35+2 so I really wouldn't worry about a few days although I know that's easier said than done.
zzzebra · 21/03/2021 11:05
I would try not to worry about it, it's completely normal.
With both my first and my current pregnant I had early scans. At both they took multiple measurements and the date varied by 5-6days.
With my first I was dated back by a week at my early scan and then by an extra day at my 12 week scan. She was born early and at 8oz 6lb, I'm very petite so I'm pretty sure the scan dates were wrong and my dates were right.