The doctors determined my due date from an estimated lmp, it was nov4 . sept 16, i got an ultrasound that read oct25 which date is accurate?

Probably LMP: Did you have a 1st trimester ultrasound? If you did, that would be the most accurate, especially if it was consistent with your LMP. A third trimester ultrasound is less accurate, with an error range of 2-3 weeks. The ultrasound would therefore be consistent with your dates based on your LMP, since there is only a 10 day difference.