Anatomy scan at 19 weeks. Baby measuring small. Should I be worried?

Lane

Went for my mid pregnancy ultrasound. 19 weeks 3 days. Baby measuring small by 6 days. Doctor said he wasn’t worried but we also referred be to his friend doctor for a more “detailed ultrasound” fetal medicine doctor. 😣 so that made me pretty scared. Even though he said not to worry. He said baby was weighing about 10oz.