How far along am I?

So based of the first day of my last period, July 1st, I should be around 11 weeks today. I believe I ovulated on the 17th. The doctor told me over the phone, my due date is April 9th. I went in for my first appointment at 9 weeks 4 days and the doctor measured the baby and said it was measuring for 7 weeks 4 days. So my due date is around April 21st. Can it really be almost 2 weeks off? So today I am either 9 weeks or 11 weeks. And I know due dates are just a guess and it doesn’t mean that’s the day I will have my baby, it’s just when people ask me how far along I am, what do I say? 9 weeks or 11 weeks?? Has anyone else had the doctor change your due date by almost 2 weeks?