HELP! Measuring Small - 31 Weeks

Emily

I’m 31 Weeks today and my doctor said I’m measuring a bit under 30. I was also measuring small at my last appointment (at 27 weeks) so she wants to do an ultrasound 2 weeks from now. Of course I am now worried that something is wrong and the two week wait is going to be tough - please tell me others have been through this and that everything was ok!?