I wanted to know the day I got pregnet if I had my baby July 19th but my due date was July 31st?

Your due date is what counts.

Just because the baby came early, doesn't change the date of your conception. Almost all babies come either before or after their due date. Hardly any come on the exact date the doctor gives you.

If you were due 7/31 you conceived around 11/8/2007

By the way, its "pregnant" :)