Pregnancy Conception Date Calculation: Based on Last Menstrual Period & Ultrasound

Question
My last monthly period first day...may 11 2008
ultrasound said my last month period was 8 weeks 5 days as of july 11. Due date is feb 24...
i was told the ultrasounds are very accurate...
when did i concieve?
i tried to send last question not sure if it send if so im sorry. Thank you for your help...if you need any info off my ultrasound if you did not recieve last message will be glad to send this info to you thank you.

Answer
Dear Brittany,

From what I calculate, with a LMP date of 5/11 and a history of 28 day cycles, your estimated date of conception would be 5/25/08. This seems to be confirmed by ultrasound. With this dating, you would have been 8 weeks on 7/6, and therefore 8 5/7 weeks on 7/11. However, I calculate an estimated due date of 2/14/09.

I hope this information has helped you and answered your question. I wish you well.

Brenda