20 weeks measuring small

Hey! I just had my half way scan. I had two dating scans and baby was measuring perfectly! So we know my dates are right. I had 4 miscarriages before this baby after two healthy average sized babies. So this little one is throwing us for a little loop.

Baby is measuring two weeks behind now and was too small to see the heart or the kidneys well enough to get measurements on them. I have another scan at some point in the next 3 weeks.

Anyone have any experience? We did genetic testing and had no red flags but, the tech and doctor seemed a little uneasy and so I am too.