Ok, I'll throw in my 2 cents, for what they're worth....
I have to agree that a .22 cal is probably not a great solution for personal protection. I've shot squirrels with a .22 rifle where it took 15 seconds or so before the creature realized that it is was all over, so I'm not so sure a 2 legged-miscreant would react much better.
The 3 things that I think are paramount in a concealed carry firearm are: 1. concealed and comfortable. 2. a firearm, be it a semi-auto or revolver that is reliable, and 3. just enough gun to do the job. My personal preference is for revolvers simply because they are most familiar to me. I'm left a handed shooter, and more than one semi auto has thrown hot brass back in my face, chest or arms. I have nothing against the Glock fans; I think the Glock is a wonderful machine, I'm just not personally comfortable with one.
We are lucky today, as we do have a lot of good choices in concealable revolvers and small framed semi-autos in calibers that are up to the task. I look to history to see what works. Most LEOs carried .38 special and/or .357 mag revolvers up until the 80s. Then they moved to the 9mm in an auto, these calibers get the job done in a reasonable size and weight. Today these examples can be had from Taurus, S&W and others for reasonable prices in sizes that nearly anyone, even a small framed lady can easily carry. Ruger has the LC9 semi auto in 9mm which is also suitable and comfortable to shoot. Beyond all of this caliber stuff is the shooter - practice, practice, practice until every move is automatic and you feel totally comfortable with the firearm and yourself. Buy enough gun, but make sure it works for you and you work at learning it.