Bad Planning - Ideas for a 10 sqm Master Bathroom

Thank you for your suggestions. There will be no additional room on the upper floor as there is no space for it, and the maximum size and budget have also been reached. There is a walk-in closet with enough space for everything, but it can only be accessed through the master bedroom, and I find moving the washing machine there less ideal, even though it would be possible from the downpipe (kitchen/pantry is below).

The walls to the two children's rooms are made of solid 17.5 cm calcium silicate bricks, and the good Miele spins very quietly compared to the competition. The noise disturbance is probably not much higher than if I place the machines directly in the upstairs bathroom. With a width of 1.25 m, there is enough space to store a three-part laundry basket and the drying rack. There is also sufficient room for all the detergent and above that, the towel arsenal or toilet paper, etc. I also think that our little one would prefer to throw the laundry there rather than going through the master bedroom. Not to mention that going downstairs is even less likely.

Oh, and the two children's rooms have a floor area of 17.1 sqm. So they are very generous, and all the child's clothes have to fit in there as well.

I notice that the sketch can be misunderstood. So the red rectangle is the niche WITHOUT wall. There is only the door in front of it. I will edit the image and replace it.