Final stage floor plan: Is there still potential here?

The knee wall is damn small. Isn't there any way to do better? How about at least 1.30m?

1.45m can hardly be used as a shelf, I wouldn’t box it off that far, and the bed with the headboard by the bathroom is also suboptimal.
Rather pull the knee wall forward a bit and behind it, at most, have storage for rarely used items (you have to crawl in there anyway) like a guest bed, the stepper you bought in a fitness euphoria but never use, etc.
You can also stylishly combine that with an illuminated shelf for the bed:



I would leave the dressing area as it is and, if it needs to be separated from the sleeping area, do so with built-in wardrobes and an access separated by a door:



I hope you can make out my scribbles:
The continuous dashed line is probably the area from which you can use the room. Slightly behind that, I would pull the knee wall in the bedroom forward as the head end for the bed, possibly with a recess like that and with lighting as in the picture above. On one side, you can make the space behind accessible through a hatch, well, more like “crawlable” (here on the left side of the plan, but it can also be on the other side of the bed).
This way, I can make the bedroom a bit smaller and enlarge the bathroom, and then possibly the shower would fit behind the door in the bathroom or something else.
The dressing area can, but does not have to, be separated from the bedroom by a wall. You could also have a custom built-in wardrobe made by the carpenter with a door to the bedroom. Just like the other side of the dressing area: the wardrobe also has a slant here if you don’t put in a dormer. Doesn’t matter, the carpenter just makes appropriately adapted shelves there, and the evening dresses hang right at the beginning, where the wardrobe can go up to the roof.
A seat for the lady of the house in front of the window. (I dare say this crazy idea comes from some movie where the protagonist has a huge dressing room with a chaise lounge and it’s just so chic; in real life, you’d hardly sit down in the dressing room, I’d bet my head on that)

I just think - excuse the expression - it's so cool! what you are doing there. I have to discuss all of this with my girlfriend as soon as she gets home from work. For your information: the room has a ceiling height of 1m starting at 32.7cm and 2m ceiling height starting at 1.44m. Yes, the knee wall is "damn small" that's true. We could possibly get it 25cm higher with a special permit. That would be the maximum possible without exceeding the eaves-side wall height. I haven't really understood the advantage of the separated dressing room so far. I would also suspect that the walls of the children's rooms should run above the load-bearing wall from the ground floor. Therefore, it might not be that easy to make the dressing room smaller by saving the one wall to the bedroom. But maybe I'm misunderstanding something here. Shower directly on the bedroom wall is possibly not ideal either :/

Yes, the knee wall is "damn small," that's true. We might possibly get it 25cm higher through a special permit. That would be the maximum possible without exceeding the eaves-side wall height.

So could we at least try around 90?!

Shower on the bedroom wall is not as loud if the pipes do not run along there.