9th percentile

Hey everyone. I had my anatomy scan today at 18 weeks and 2 days. Baby girl is measuring in the 9th percentile. I know this means she is measuring small but what does the really mean?? I’m freaking out. Anyone had this happen and everything be okay? I was very sick the first 3 months of pregnancy and just now getting my appetite back so I want to think it’s because I haven’t been eating enough but I’m not sure :( starting a high protein diet today and hoping that helps.