I found the Kahr PM9 to be the smallest manageable 9mm for me, and I have been down this road for 50 years, even the Seacamp "off topic" was too small to get a proper grip on. The PM9 is the smallest manageable gun, "with some grip tape" for me, it's been 5 years now, and it still shoots anything I put in it.
Don't get too hung up on "the smallest", the hand and fingers need a specific size to work with, and sometimes having the smallest doesn't equate to the best for you. It has to be able to come out of hiding fast and in position to fire rapidly every time. Having a slick small gun, could end up on the floor if you are nervous and your hand is sweating, "mine don't" but some guys do. So there is small and unmanageably small, are your follow up shots going to be there when the gun recoils and slides a fraction of an inch out of position, shoot some small guns and see which one works for you under simulated stress,. Even unload it and see if you can get it out and make a shot.