Enlargement of the bathroom in the attic including the sloping ceilings

Hello everyone,
After we abandoned the plan to convert a study into a bathroom, it is now certain that we will enlarge the existing bathroom in the attic of the house.
We want to turn a small shower bathroom into our new main bathroom.

The wall, as can be seen in the pictures, is already gone. Now a new drywall partition is to be built.
The goal is a bathroom with a larger, walk-in shower, toilet, and a large washbasin.
I have attached an initial plan.
In the back right corner are the fresh water pipes, and the wastewater pipe is also located in the chimney.

We would tile the shower tray, and the box at the end of the shower is supposed to be a kind of footrest.

Unfortunately, we currently cannot think of any other room layout that makes sense. Do you perhaps have an idea?

We would tile the shower tray, and the box at the end of the shower is supposed to be a kind of footrest.

Thank you in advance for any new input!

You probably won't have many options in the inventory. The water and wastewater for the sink are possible as shown? Will the radiators remain as they are? Maybe you could also mention the knee wall height and the angle of the roof slope so that the 2m line can be drawn. I find the box you call a footrest ugly. What is it supposed to be good for? Better to just put in a dwarf wall right away. But it depends on the heating.

Toilet belongs in a room like this under the slope (pay attention to the 2-meter line), so that there is headroom for the rest including walkability. Dimensions would be nice. And what the bathroom is used for (large family or couple, how many children?)

No feedback is also feedback. Thank you.

No response is also a response. Thank you.

I don’t see that you wrote anything before? I am grateful for any reply, but in between I am also busy on the construction site.

You probably won't have many options in the existing building. Is water and wastewater for the sink possible as shown? Are the radiators staying as they are? Maybe you could also mention the knee wall height and the angle of the roof slope so that the 2m line can be drawn. I find the box you call a footstool ugly. What is it supposed to be good for? Better to just install a knee wall. But that depends on the heating.

The radiator at the current sink will definitely be removed.

The knee wall is 65 cm, angle 45 degrees, so the slope is very low.

Water and wastewater should work like that.

The box is not really intended as a box; the bathroom planner couldn't represent it better. A knee wall is of course more sensible here if the shower is built like that.