I would not recommend a shotgun for a small woman. It packs a kick. Far better to have a .223. There is far less kick and the user wouldn't procrastinate practicing because they dreaded the kick back
Not saying your wrong, but two comments:
One argument that people use for a shotgun vs. a high velocity military round has to do with collateral damage. e.g., hitting your kid in the next room or your neighbor in the next apartment over.You make an excellent point. And this is where it gets complicated.
The first thing is that people need to know their tool and the only way to do that is to use it. I hate hearing people say "just get a shotgun." (I'm not speaking about anyone in this thread. This is a general comment.) I hate hearing it because too many people get a shotgun or say a Desert Eagle 1911 chambered in .45 ACP and then never practice with it because it "hurts their hands" or their shoulder.
It doesn't make sense to get a tool; never use it; and then when your life - and the life of your children - are on the line have to use it. I've never been in the military and never pulled out a firearm in self-defense. I'm damn sure that if that day arrives I will not shoot as well nor be as level-headed as when I'm at the range.
And there's no reason for anyone to be embarrassed about not wanting to shoot a particular caliber because it hurts their hands (or shoulder). IF you find that to be the case you need to find a round that you can handle, and then practice with it.
Ok. Rant is over.
Re shooting through drywall and hurting your children or your neighbors - you raise an excellent point. I have a Mossberg 500 - or did. I now live in a deep-blue area where such evil things are not permitted.
What's the best caliber? Boy does that open up a can of worms. I can't rightfully answer. And, if I tried, I would contradict myself a hundred times.