EDD via ultrasound

Hello po. Ask lang ako any idea kung ilang wks nanganak yung iba iba edd kada ultrasound. 1st ultrasound(transv): edd is oct 20 2nd utz:edd is oct 16 3rd utz: edd is oct 15 Dko na tuloy malaman kung ilang wks na talaga tyan ko hehe. Natatakot ako maoverdue. No signs of labor as of today. #2ndpregnancy