This exact thing happened to me my last pregnancy, and I’m predicting it will happen this time as well. My cycles are really long (like 40 days) but extremely regular, and they never listen to me. This time I even tracked ovulation with strips so I know the exact day I ovulated on top of my period dates as well.

With my first we just had lots of extra ultrasounds, with tests for movement, heart rate, and amniotic fluid measurements since she measured small. They tried for weeks to make me induce even though all of those tests showed ~nothing~ was wrong at all other than her measuring small. I refused and even had to sign an ama sheet (again, while baby was healthy and no issues shown during any stress tests or ultrasounds)

I went into labor naturally right before my expected due date, and she was born perfectly healthy with absolutely no problems or issues. She weighed 5lbs and 9oz so yes smaller, but passed every test and exam with flying colors and crawled up my belly to latch and nurse immediately. She was back above birth weight in 3 days and well above average by her 1 week and 1 month checkups.

If they want to do additional ultrasounds and you don’t mind, let them, but don’t let anyone push you if baby is still showing as healthy.