My due date is August 4th

It can vary a bit but most likely sometime early November.

Due dates are estimates, normally from sonograms are use average size of infants at certain times of development, some babies are ahead and some behind, thus why they are averages.

So often give or take a week, even two is not out of the ordinary. There is no way to know an exact conception date ( unless you only had sex once within the entire window of time)

So unless there is a issue of different partners there is no real issue or way to point to an exact date. If there was sex with different partners within a week or even two of each other, you will have to do a DNA test when the child is born to be 100 percent sure.