I have had a few small .22lr autos. I have had, a Beretta 21A, Taurus PT-22 (Beretta rip off), Jenning J-22 and a Bersa 23 (kind of large).
Out of these only the Beretta is reliable enough to use as a CCW. The Taurus was a jam-o-matic even after TWO trips to the factory at my expense (the work was free but shipping is expensive if you have to ship the entire gun). The Jenning was decent for a few hundred rounds and was very accurate but made poorly and reliability went down the more rounds I fired. It was cheap ($50 new) but it never broke. The Bersa is a little large for what you are after but it is very accurate and as reliable as a Ruger MKII or Browning Buckmark.
The only one that is small and reliable in my experience is the Beretta 21A. With ammo it likes, it hasn't jammed on me yet. It doesn't like Winchester X-pert or Winchester Wildcat ammo but will feed many other types of cheap and expensive (relative to .22lr) ammo 100%. I carry CCI Stingers and shoot cheap Remington ammo for fun and practice.
I had a Kel-Tec P-32 that was as bad as a gun can be. It was unreliable and it broke on me after about 400 rounds. Even my Jennings J-22 didn't BREAK and I must have shot several thousand rounds through it. I would be wary of anything made by Kel-Tec until they have developed a reputation for reliability.
There is no sure thing in the world of guns but if you are looking for a reliable, tiny .22 auto, I would start with the Beretta and maybe save some money. I think the 21A is as good as it gets in a .22lr of this size. If the 21A doesn't work, I don't know to tell you. If my Beretta starts having the kinds of problems that I have had with the Kel-Tec or the Taurus, I am going to give up on tiny autos and just get a Ultralight S&W snubbie and be done with it. I probably should do this anyways but I am waiting on a deal, I can't see spending $600 for a gun that someone will sell to me for $300 once they find out how much they kick.
Some people buy them and can't handle the recoil and then sell them cheap, that is what I'm waiting on.