Where is the door in relation to the dimensions? On a short wall or a long wall?

Ideally, it'd be on a long wall, but I am guessing that is not the case. (and centered would be perfect).

Current config:
The door is on long side facing the wc, almost on the corner. In the left corner is a sink with an absurd wrap around counter/cabinet all along the left short side.

Here is a photo.

That is absurd.

I'd consider setting up a wet room. Shower across the back, long wall; door in center of other long wall.

Sink on one side of the "front" of the bathroom. Toilet on the other side of the "front" of the bathroom.

Take heart! Here is an even SMALLER bathroom (67" x 43") that was made over to spectacular effect ... Could something along these lines work for you?!

Good luck with your project!
Ruth

Here is a link that might be useful: Small bathroom makeover