Personal carry and home defense. First thing I'd do is rule out the 45! To much recoil and the one's I've seen are to thick, to big and heavy for concealed carry. That's not to say you can't, guys do it everyday. I'm and old guy! How do you shave weight and size? Smaller frame, shorter barrel and single stack magazine. Cartridge much more shooter friendly! I carry a S&W Shield 9c every day. Very light and very comfortable and 9mm is pleasant to shoot. I keep it on the headboard at night along with a Ruger P89. I really doubt they will ever be needed but if they are, I've got a gun that carry's well and is comfortable to shoot. The Shield has a single stack magazine, make's it thinner than any 45 I've ever seen. It has a very short barrel. Along with a single stack magazine, makes it much lighter. Shorter, thinner, lighter and shorter barrel make's concealment much easier and remove's a bunch of weight that, for an old guy, will add up. I prefer DA's in handgun's but, my 38 is much larger and much heavier. Shot a friend's S&W Detective Special with factory ammo once, to much recoil for me. I know I wouldn't shoot it in practice enough! The idea that you'll need more than five or six round's I find bogus but should you need six, with an eight shot magazine, You have two or three extra shot's. Say you actually do need a seventh shot, you'll have to reload a revolver and no way can that be done quick as a auto loader. Some extra fire power while keeping weight down is a plus for me. I also carry one extra magazine. If I need more than one it would shock me. I do have a double magazine pouch I seldom use, add's more weight!
In home defense, unless you are a bad guy, I suspect the biggest detriment to attack is noise. People that break into your house want to steal something, not get shot or even risk getting shot. 99.9% of the crooks that might break into your house will be looking for a way out when the first shot goes off. I suspect the intruder won't even be armed. I read that from a retired burgler year's ago. He said the worst thing to do in his line of work is to carry a gun! He's there to get the jewelry, not shot and if he is caught, he's didn't want to be caught with a gun.
I would not get to paranoid about this business unless you live in a place like Chicago. They shoot people there for practice. One light weight concealable gun with one extra magazine I believe would do fine. In fact if I were thinking of going somewhere I might need more, I wouldn't go! Some guy's have their primary gun, another in another spot and for the final act some kind of fighting knife! To me, that is the definition of paranoid! You should be able to defend yourself, not prepare for combat! I believe that most confrontation's will end with the sight of your gun! Unless your in a place like Chicago!