We had 26 cm, which we enlarged to 27 cm with metal edges - and that is one point we would do differently in the next house (although it is still okay). The problem is that a design often stands or falls with the staircase - however, you could simply extend the staircase by, for example, setting the front door back - you would no longer have a porch, but more light in the hallway. I would: move the door back to the wall at the bottom of the plan, remove the window by the wardrobe, place the wardrobe against the wall at the bottom of the plan. To maintain the symmetry, just remove the window in the office as well. Then you can also make the bathroom a bit (10-20 cm) wider and relieve it a little. Dimensions would be nice ;)