Due date calculation?

Ann Marie • 35, Boston area. I have a 2-year-old son, pregnant with my second, due July 2018
Do all doctors calculate the due date from the first day of your last period? I know that I didn't ovulate until 2 weeks after that (thanks Glow!), so should my date be two weeks later? Glow is calculating from the first day of my last period, as are the nurses who scheduled my first two prenatal visits. This is my first, and  I don't have my first dr appt until 8-9 weeks, so I'm curious :)