Your due date is 11th sept 2010 given by the doctors so you want to know iam in which week of pregnancy and when should you visit at your place for the delivery?

add 281 days to to your LMP to get expected day of delivary

Due Date CalculationPregnancy, on average, lasts 267 days (38 weeks) from conception. If you positively know your conception date, you can add 267 days to it for your due date.

The following formulas can also tell your EDD:

Date of the first day of your last period + 281 days = due date

or

Date of the first day of your last period + 7 days - 3 months = due date

The methods here are based on the average 28-day cycl