Congrats auman!!! Savor the experience with your son and don't beat yourself up. I've had much more regret passing those deer only to have them wind up on someone else's tailgate, than I have on the ones I or my kids have decided to kill.
Matt hits the nail on the head again. In today's Alabama deer hunting world, if you are only gonna hunt and kill bucks 5 and older, unfortunately you will have lots of years with nothing to hunt. Ask me how I know.
Location, location, location and even then, luck, luck, luck on keeping one alive long enough.