Low Weight Percentile

I found out that my baby dropped from the 13th to the 3rd weight percentile at my 28 week (I was 28 weeks and 5 days) appointment. She only weighs 2lbs. My doctor basically said that she’s either perfectly fine and I just make small babies or there could be an issue with her getting consistent blood supply from the umbilical cord so she’s sending me to a specialist to do a Doppler ultrasound to double check.

My placenta and fluid look perfect and the baby is super active. I’m just so worried now...has anyone else experienced something similar and had a good outcome?