I will assume you are talking about Feburary 11th 2012. If so, your estimated conception date is May 20th 2011. However, this date could be wrong by a couple of days. It also depends on when you ovulated.
Count back nine months from your due date.
March
The approximate date of conception was July 7th.
march 21
go to babycenter.com and use the due date calculator
The approximate date of conception was May 2nd
Roughly March 6th
in march
April
may 16th
6th June
July 17,2008