As a couple of people have suggested, if you think the 9mm is insufficient don't carry it unless or until you change your mind. If I am going to only carry 7 (give or take 1) rounds in a gun, it is probably going to be .45.
.45 because shooting something twice is silly... and it's God's caliber.
Just kidding, tongue in cheek, ect...
I used to carry a 3" SP101, never felt undergunned with that sucker but damn it was heavy for its size. Switched to a 3" LCR-X but just didn't like it as much. Friend of mine had a Glock 36 that I tried out and I shot it really well. Have been a revolver guy for years and finally turned to the dark side...
Having seen a whole lot of people shot, I'm caliber agnostic at this point as far as the common duty calibers. Used to be an archbishop in the church of the .45. The simple truth is any of the major duty calibers, using quality ammunition, do their part if you do yours. Ammunition selection matters more than caliber selection at this point. A general recommendation is a heavy-for-caliber hollow-point that retains mass, either through bonding or mechanical locking of the jacket.
I currently carry a 9mm. I'd just as readily carry a .40 or .45, or a .357. The differences are largely angels dancing on pinheads, again assuming you selected a good cartridge.
For what it's worth, during my law enforcement career I personally observed and investigated far too many failures of the .38/9mm class guns to carry them as my main combat handgun. I consider them fit only in a BUG capacity.
My personal carry guns includes wheel guns and self-loaders starting with .41 Magnum through .44 Magnum and .45ACP.
Adapt to whatever you can manage to hit your target consistently and with the most speed but remember Bigger Holes Leak more Fluids.
For what it's worth, during my law enforcement career I personally observed and investigated far too many failures of the .38/9mm class guns to carry them as my main combat handgun. I consider them fit only in a BUG capacity.
My personal carry guns includes wheel guns and self-loaders starting with .41 Magnum through .44 Magnum and .45ACP.
BBI, how in the world are we supposed to talk trash about calibers other than our favorite when you come in here with a bunch of experience, common sense, and real-world examples. Huh, answer me that. It's blasphemous I tell ya.