Consider another caliber
To the OP:
Please consider another caliber for self-defense. Unless you have a medical thing that makes the recoil of heavier caliber impossible, upgrade USAP. It's kind of like the "5 or 6 shot revolver/multiple assaliants" argument in that more rounds will need to be pumped into the first, then second BG and so on. The hitting power of 380, 38, and 9mm caliber can be affected by denim jackets, heavy sweaters and flannels, leather coats, muscle tissue, etc, but are enough plenty enough to wound. The 22's ballistics DO work, but only with a direct hit to the head or neck aka ideal conditions. If you hit a BG with two 9mm in the shoulder, he or she will be worse off than two .22 LRs in the same place. Sure you can get shots off quick w/ the low recoil, but what if The Guy Who Broke Into Your Place Is On Meth is Armed with a Gun or Has a Sword.
For Gosh sake, i'm guessing you are not elderly or medically compromised. If your a healthy guy and have a job, keep the 22 as a range/fundamentals gun. A lousy $450 on gunbroker will get you a S&W 38 Spl 642 J-frame revolver, or a used S&W 9mm Sigma, or a Ruger LCP in .380 if youre recoil sensitive. Don't just stick with the 22 because "well, I already have it, so... and the ammo is cheap, ya know."
You're already competent enough to own and operate the 22. Use the logic that 380/38/9/40/357/45 are the better SD caliber and Make the investment.