Due date confusion

Pam
Soooo... my LMP was Feb 27 so that would give me a due date of Dec 03..... but when I went to my two ultrasounds they told me my baby was measuring one week more so they put my due date Nov 27 (tomorrow).... so im so confuse bc the doctor is still going by Dec 03.... so lets say by monday i still dont give birth would that mean im late???? Idk but i hope i give birth tonight/tomorrow!!!!
Anybody else went thru that and experiences!?