Measuring behind? Anyone else?

Im 30 weeks and 5 days and the Doctor told me I was behind measuring about 29 weeks. Last check up 2 weeks ago I was measuring perfect. All 3 of my boys were 6-6.9Ilbs all induced from being small, I'm just really stressing since my last delivery/emergency csection I had complications which resulted in them not letting me go past 37 weeks with this baby. I don't want him in the NICU and I'm terrified that his lungs are not gonna be ready. My growth scan is in 2 weeks, but I can't stop thinking the worst is gonna happen.