sasayeo, if your ovulation is exactly 14 days after 2 March, then like what chubbyfingers say,
should be 10 weeks..
but if your ovulation is late for 1 - 2 weeks after your last period, then your EDD can be delayed coz it's supposed to be based on actual.
I guess during the initial period, it is probably accurate that gynae get the EDD by measuring baby's length.
during my #1's time, the first gynae told me i had miscarriage coz he only based on LMP and then couldn't see fetus during the initial scan.
when i went to scan at hospital, they could see. so i think it can really vary by people.
for me, this time, i used the ovulation kit during TTC period so i know the date of my ovulation.