Ultrasound measurements

Triniti • After multiple loss our angel babies are our guardian angels and we have a rainbow baby is growing! Gonna announce it memorial weekend!
So the measurements of my baby boy per ultrasound is measuring 8 days early now... Was just 5 on the last one. I'm due date since the beginning has been thanksgiving and they won't move it up to what I'm measuring. Anyone else experiencing anything similar? Or have in the past?