How far along am I??

So when I first found out I was pregnant, based on my calculations, today I should be 13w1d. I had an ultrasound done a little over three weeks ago where they told me I was three days less than what I thought I was. At the time I thought I was 9w5d, but measurements said 9w2d. I had the NT ultrasound yesterday, and based on that new gestational age, I was 12w4d, but when she measured the baby she got 12w6d the first time 13w1d the second time and 13w2d the third time! So how far along am I??  Here's my little nugget 😍 (the US says GA: 12w4d which is what I was given with the first measurement 3 weeks ago, but I'm doubting that age now).