If i am due april 22 what would be the date range of days i had to have sex to get pregnant ? my periods are 33 days apart?

Easy to count: In a natural pregnancy that got a due date estimate through an ultrasound scan, one can grab a calendar and just count back 38 weeks to the estimated conception date. The estimated date will be plus or minus one week, but is a pretty good guess at when conception happened. Of course, nobody ever knows exactly when a natural conception happened. It is impossible to know that.