This may be a stretch, but you may have what is known as a "PX Luger". At the end of the war, Krieghoff made a number of P.08 pistols from mixed maker parts (Mauser, Simson, Krieghoff) for sale to US GI's while.occupying Germany. I recommend taking a dozen good pictures of this luger from every angle and sending them to the owner of Legacy Collectibles. He has been identifying lugers for a long time, and can likely help with this mystery (usually free of charge).

Here is a PX Luger with no toggle markings:

Rare PX Luger - End of War | Legacy Collectibles