I don't think your numbers are accurate however even if they are there are hundreds of thousands of instances where someone defended themselves with a gun where nobody was shot. You don't need to fire the weapon to successfully defend yourself
I got the homicide numbers from the FBI. According to their records, 2014, there were 229 justifiable homicide (killing someone in self-defense) by firearm committed by private citizens. There were also some justifiable homicides by other methods (knives etc), but I don't have the data in front of me right now like I did when I wrote this comment.
It's more difficult to get an accurate estimate of how many people used a gun in self-defense without shooting the other person. Some people have tried to study that, but it seemed like it's tough to get an accurate figure because it relies on self-reported data and "have you ever defended yourself with a gun?" is sort of a broad question.
(Edited because I typed the wrong word.)