Baby details, please help:)?

Okay so me and my fiance recently found out we've finally conceived :) we'vve decided on making a scrap book for our little one with all the details of our pregnancy . myy last menstrual period was feb 20th 2011 and my due date is nov 24th 2011 , when did we likely concieve?? Thanks to everyone who answers , this really is a joyous time for us .