Gestational Age..

Kay
So today I had my second anatomy scan (23+3) because they couldn't get good pictures of baby's heart...Same thing today but I was measuring 23+6 (still no good pictures since baby wants to be stubborn) lol but yesterday when I went to my regular ob I was measuring behind (probably due to baby's position)...Question is do I go by 23+6 now or 23+3? Doctor said my due date "will definitely change" I just have to return in 4 weeks to see when it'lll be...