Brightening on intestine and measuring small

Had my 20 weeks ultrasound (found out we are having another girl)

and she said we had a generally healthy baby but was measuring small and had some brightening on the intestines which might of been caused by swallowing blood early in the pregnancy or might be connected to being growth restricted ... but there are also some chances of a virus or Down’s syndrome but she said it was highly unlikely ... she scared me because I have to go back at 24 weeks because that’s when a baby can survive and if the growth isn’t looking better start talking about early induction I had my last girl at 34 weeks and she is completely healthy but I’m terrified I just want my baby to be alright even if she does have some disabilities I just want her to be healthy and not come before atleast 30 weeks ... has anybody else experienced any of this and had a perfectly healthy baby? My 12 week ultrasound was perfect now all of this 😕