Measuring 10 days behind when I tracked ovulation/bfp

La

Feeling discouraged. My LMP was 1 AUG and I got my positive opk on 15 AUG. I got my BFP on 27 AUG. I should be 8+4 but I’m only measuring 7+1. I had an ultrasound 10 days ago and the baby only grew about 4 mm since then but the heartbeat went up from 119 to 162. Feeling really discouraged. 😔 anyone have stories or insights? I go back in two weeks.