[Chickensoup]

No joint in bottom of both thumbs. Hurts and impairs grip.

[mylife]

So you probably require something with a large grip and low recoil.

I suggest a full size 9mm like the barreta M-9

[mylife]

I think you need something that will “fill” your hand that has low recoil

[Soliton]

No joint in bottom of both thumbs. Hurts and impairs grip.

You will probably not be able to operate the slide on an auto. My wife can't due to arthritis. You will need a revolver. If money is no object, a LadySmith is a beautiful gun. Avoid single action revolvers however. You have to use your thumbs to cock them. Go double action or hammerless.

[Cicero]

I’d also advise trying to find help from the NRA, maybe a shooting range where you can get some training and try out various weapons.

IMHO, a .22 is adequate for most purposes, unless you have a real bull of a man charging you. The average homebreaker is likely to be a coward and reluctant to face any weapon. But it might be best to consult an expert and give various types and sizes a try.