I am confused, how is this possible... maybe tmi?

For some strange reason doctors consider you two weeks pregnant at time of conception! so what ever date you thought you conceived if you know then add two weeks to that and that's how far along you are I was so confused as well when I went on my first appoitnment I knew I was 4 weeks based on conception but they added to weeks to that because they go based on the first day of your last period why? I dont know. Congrats and good luck!