According to my LMP I am almost 5 weeks along although I O'd on the 4th of this month. Would I still technically be almost 5 weeks or almost 3 weeks? I have this fear of setting up my first dr apt and then the Dr thinking something is wrong because the baby measures 2 weeks behind. I have no clue how all this stuff works. This is my 3rd but I never actually knew when I got pregnant before. This time I am pretty sure it was when I O'd at the beginning of this month since last months period was right on time and normal length. Do I just tell the Dr when I see him when I ovulated and that I am pretty sure that is when I conceived? Hope all this makes sense.