Pregnancy conception

Patient: I am currently 21 weeks and 2 days pregnant my due date is march 18th 2015 if these are correct! Could I have conceived before the 14th June 2014?

Doctor: Hello,thanks for contacting askthe doctor.comThe period of gestation is calculated from your last menstrual perio d.For the EDD, you need to add 9 months and 7 days to your LMP as per naegle’s formula and you would get your due date. You may calculate accordingly.i hope i have answered your queryregards