I would leave out the walls. The bathroom becomes too small. Although 11 sqm is not exactly little, partition walls are barriers, so it suddenly looks like only 7-8 sqm. Windows can still be changed after the building permit, as long as you don't turn a normal window into a panorama pane. At least the window facing the street should be fitted with a parapet, otherwise going into the shower becomes a peep show, even with a blind. Terraced houses often only have these 2.40... we had 2.25 with a classic layout. It works for two people, but with a family I would also prevent bottlenecks. I like the toilet opposite the shower, but without a privacy screen.