This comment is going to draw the ire of others more than anything.
Your last post is flawed greatly, but I will not attack you, but set forth a few questions to assess what is what here.
Have you ever had any training with a professional? If not, I highly suggest it. There's a lot to be learned, even by those of us who carry weapons for a living. There is no such thing as over training.
Never ever underestimate person wielding a knife. Ever. (And here is perhaps the best argument for a larger bore self defense pistol) if someone can get within 15' of you with an edged weapon before you have drawn, your toast. We are trained to take them inside before they get inside 20', but better at 30'. It's a fact, and the closer they are, if you are drawing and firing from the hip for center mass (something you should train for), I'd rather the punch of my .45 than a 22lr.
Train up. That's the bottom line. I would carry a 1911 in 45 if you are comfortable doing in 22lr. You can't justify less collateral damage. Any at all will be unacceptable. And the more training the less chance of this. High pressure situation training is way different than going to the range, sign up for a course and test yourself. I guarantee you will re evaluate your thoughts