If my last period was Nov. 17 2007 and my due date is Aug 15. 2008 what was my conception date?

It depends on your cycle, according to the date you provided of your LMP here are your possible conception dates. On average, ovulation occurs 12 to 16 days before the menstrual period begins...

Conception date - 25 day cycle: November 28, 2007
Conception date - 26 day cycle: November 29, 2007
Conception date - 27 day cycle: November 28, 2007
Conception date - 28 day cycle: November 29,2007
Conception date - 29 day cycle: November 30, 2007
Conception date - 30 day cycle: December 1, 2008
Conception date - 31 day cycle: December 2, 2008
Conception date - 32 day cycle: December 3, 2008
Conception date - 33 day cycle:December 4, 2008
Conception date - 34 day cycle: December 5, 2008
Conception date - 35 day cycle: December 6, 2008
Conception date - 36 day cycle: December 7, 2008
Conception date - 37 day cycle: December 8, 2008
Conception date - 38 day cycle: December 9, 2008