There is more confusion. Ezell shows a pistol identical to yours (No. 22) marked "Mauser Werke A.G." a name not used until 1922. So while your pistol could have been produced before 1922, the Ezell gun had to have been made in or after that year. But, according to other sources, Nickl himself went to Czechoslovakia in 1919. That would not mean an end to Mauser work on his designs, of course; they owned the designs and could certainly have continued to work on them without Nickl himself.
But another puzzle. No. 22, identical to your gun, has the "Mauser Werke" marking, while No. 29, with the modified slide and slanting serrations, is marked "Waffenfabrik Mauser". There is no doubt about the order of the markings and the date of the official change, so somehow there must be an explanation of the anomaly in the markings. No. 29 simply looks newer, and less like the old Mauser pocket pistol; yet the markings don't jibe.