6 months pregnant with twins: scared the gender scan is wrong

I'm having twins and because they are right on top of each other it was hard to see the gender. After looking for a while with the tech , a doctor came in and gave it a go . She said they were both girls ! I'm deathly afraid to give birth and one is a boy ! I'm 6 months so I know they will look again but until I get a 100% confirmation I live on edge about it being 2 girls !