It is hard not to worry isn't it? That is what mummies do!! Scans are only and indication as is the funfal height measurement o bubs size and they can be out by quite a bit. Plenty of mums have been told their bub is too small or big and the baby is absolutely fine. If you are getting worried give your middy/provider a call and have a chat about it.

My SIL's bub always measured small and she was born small but perfect and healthy.

Goodluck