I gave birth on the 4th August 07. She was 3 days late. Pregnancy went well with no problems. My periods are regular up until my last lmp was on the 24th October 06 giving me an estimate coception date of 7th November 06. I also had a vaginal scan first week in December 06 which dated me around 6 weeks as thought. Is there any possibility that I conceived first week in September 06?

There is no way you could have conceived the baby during the first week of September.

No, they would have picked up a two month difference... you would never have gone that late.