Try this simple drill.
Put up a piece of plywood, 18" across by 24" tall. Draw a line down through the center, another one across it about 9" from the top.
Stand facing your target at 25 yards.
Start walking towards it at a normal pace. About halfway there, draw, come to a modified Weaver while still walking and start shooting 2 shots per pace. Aim where the 2 lines intersect.
Reload as you need to, continue to shoot until you're 3 feet away.
Any hits on the target count. Any hits within 3 inches of the intersection of your lines is a kill.
Count your hits compared to shots fired. Then look at that huge fucking group that you just shot and remind yourself that it was a handgun, not a shotgun you were shooting.
My point is that self defense shooting very seldom happen at the range unless you happen to live in Los Angeles. Find a place where you can shoot different scenarios, even if it takes a day trip. Take lots of ammo, plywood, and lunch. Have fun and shoot from every damned angle and cover you can think of.
It may save your life, even if it just serves to show you that you ain't as good as you thought you were.