Baby measuring behind

Madison

Hi, I am kind of stressing out. I went to my anatomy scan yesterday at 21+4. The baby is measuring almost a week behind where she should be. Should I be worried? They have me going back in 5 weeks to check she is growing still. I am nervous because she’s smaller than she should be. I know she has a lot of time to catch up, it just makes me nervous. Does anyone else have experience with this?