Measuring behind, doesn’t make sense...

I had my dating ultrasound Monday, July 5. According to LMP, I should’ve been measuring 9 weeks, but going off the day that I’m 95% sure I ovulated (I have 35-37 day cycles), I would have measured about 8 weeks. Baby was measuring 6 weeks, 3 days, with a heart rate of 114.

I’m 30 years old, this is my fourth pregnancy, and none of my other babies measured behind at their dating scans. I’ve always been spot on with ovulation dates, considering my long/ irregular cycles, but I suppose there is a small possibility that I could have ovulated later, but still doesn’t add up in my head.

I have a reconfirmation scan August 4th to see if the dates are still lining up with last week’s scan. Has anyone else experienced this? I’m trying not to worry myself, but I can’t help but get sucked into all of the negative possibilities...

*Side note* My last baby was diagnosed IUGR at 33 weeks when there was no change in growth from 31 weeks.