Anatomy scan- baby measuring tiny

Just got a call back from my doc after the ultrasound. She said baby looked proportional and nothing to be concerned about BUT baby is measuring 11ounces at 21 weeks (10 percentile)

My husband and I are both tiny, my first born is and has always been low on the percentile cause of her genes as well

But along with that the doctor said the cord was on the side. Whereas it might not commonly cause problems it can cause slow growth in babies and so I’ve been told to return for an ultrasound in 3-4weeks to see baby growth.

I know she said to not worry but I can’t help it 😰

Is anyone going through the same thing or might’ve experienced this?