i have done both one is 20th of october the other the 12th of october not sure which one is right...specially since i started raking metformin on feb 15 ...
There are also due date caclutors online which should be easier and it will give your all your info.
Take you last period the month Jan subtract 3 from the month so October and the day 5 you add 7 to that 11 so, October 11 2013 they always say give or take 2 weeks from your due date. My last period was Jan 9 Im due October 16 i will be 10 weeks Wednesday. I hope that helps you.