I'm still confused by the differences in judging how far along one is. I know you can either go by your last menstral period, or by when you ovulated... so which is most commonly used and which is being refered to in pregnancy books and online??? My last period started on June 18th, my OPK shows I ov'd on July 1st... my cycles were a little irregular (24-29 days) so I'm estimating my due date being around 3/23/04... that said how far along am I considered now? Is it approx 4 weeks (from last AF) or is it 2 weeks (from OV)???