New bathroom planning with sloped roof: floor plan design

Hello dear house-building forum,

we are planning to build a single-family house for 3-4 people in Lower Saxony.
We have to finalize our floor plan in 2 weeks and are still not 100% satisfied with the bathroom layout on the upper floor.

We would be very grateful for ideas!
Attached is our current draft.

Knee wall: 100cm, roof pitch 45 degrees, red lines = 2m or 2.20m
Windows: double casement windows (not floor-to-ceiling) facing north

Next to the bathroom there is a storage room and a bedroom. We can still move the walls. We can also freely place the sanitary fixtures.

Our bathroom is relatively large, but due to the sloping roof and the door and window positions, it is difficult to furnish.

What bothers us a bit about the current draft is the large niche behind the shower (maybe enlarge the storage room?) and that the toilet is placed directly next to the bathtub.

What we definitely want to consider:
- Behind the washbasin there should be a shelf (wall recess).
- We want a larger washbasin (about 100x50cm), no double washbasin.
- The shower should be at least 100x120cm in size.

Thank you very much for your suggestions :)