Baby is on smaller side

Hi mummies, I’m currently week 36 and baby is only 2.1kg. Baby has always been on the smaller side (around 15-20 percentile) but this week’s scan is only around 5th percentile. Doctor say don’t have to worry too much since me and my hub are quite petite as well. Any mummies who are also experiencing this and what can i do so that baby grows more? #advicepls #FTM