It is almost impossible for us to suggest what might be best for you, as each home and surrounding area is going to be different. Plus we cannot know exactly how familiar you are with any given firearm.
That being written, a 1911 is of course going to be a fine weapon for home defense. The caveat being the danger to those whom you wish to keep safe. That danger being from misses or misdirected shots.
Virtually any weapon fired in a home can (and will!) result in penetration of sheet-rock, up to and including exiting the house proper. I would be more concerned with bullets piercing my neighbors walls than whether or not I have the "right" gun. We already know you have a fine pistol, more than capable of stopping a miscreant. Since you are not a soldier or policeman with the resulting needs of those occupations, the odds are that having a .45 pistol should prove overwhelmingly sufficient.
My suggestion is to practice, practice, practice with what you own, so as to instill a greater level of confidence with your abilities. Buy a very high quality flashlight, keep it along with a cordless or cell phone handy at all times . Beyond that we are simply discussing "what ifs" and zombie invasion.