Opinions please

I went to my doctors appointment yesterday and recently my baby has been measuring behind a week when she would take his measurements with the tape now I’m currently 36w3d and he’s still measuring 34 weeks and its been like this for two weeks now every time she measures him with the tape he’s 34 weeks she told me that it was probably due to marginal cord insertion with his umbilical cord being slanted to the right he couldn’t be getting nutrients he needs should I be worried it’s been two weeks nothing changed ?