Here is how you test toroid (donut shape) vs flat planet theory.
Go to the edge of the known world, step over, are you in empty space?
If yes, the world is flat.
If no, check your coordinates, this point and the last one you were on match up and are next to each other.
If you keep traveling around the edge, connecting the matching points, you will find that the entire eastern margin lines up with the entire western margin, implying a tubular shape instead of a sphere.
No go to the north, and you will find that the north and south line up as well. This does not disprove the tube, but requires you to take that tube and connect the ends together, forming a donut.
Your theory of a Donut shaped world is interesting, and makes sense given the dev teams' fondness of all things Donut.