Now also from me a floor plan

I believe the perfect floor plan does not exist - only one that appeals to you without technical defects. I am also trying (in vain) with passion with a very similar room program and I absolutely agree with you: model home providers only know 2 children... if at all. And unfortunately, it is often the case that a finished floor plan cannot simply be changed without being "broken."

Regarding stair alternatives: take a look at the stairs in the attachment - certainly not good either, but maybe an approach. Otherwise, you could arrange the stairs next to the entrance (then you walk against a wall when exiting) or in the middle and a hundred more.

Removed to the left, the moderation

We are also building with 3 children's rooms on the upper floor and a cross gable. If you are interested in our floor plan, then go to my profile, where I have linked our construction diary. Our house is slightly larger than yours. I find the upper floor in your case somehow too convoluted. Everything somehow looks like a makeshift solution.