Hello, I'm at 39 weeks and 6 days of pregnancy according to my gynecol…

Hello, I'm at 39 weeks and 6 days of pregnancy according to my gynecologist. By ultrasound it's already exactly 41 weeks. The doctor absolutely refuses to agree with this dating, even though I specifically did ultrasound three times and on all scans the gestational age is a whole week later. I'd like to know at what gestational age labor is supposed to be induced? And can the gynecologist send me to be induced at 40 weeks or will I have to wait until 41? Because then, by ultrasound, it would be as much as 43 weeks of pregnancy... and I'm worried. Thank you in advance.