Above all, this small window at the top right bothers me a lot.
I understand that, it would bother me a lot too, both from the outside and the inside. I would at most plan such a small window in a guest toilet, but not in a bathroom where parents are supposed to get ready every day. I'm afraid it won't get any bigger because of the shower. It could be made as frosted glass, but it would still be exactly in your shower, opening it would be difficult.
I think the suggestion from is good, especially because of the window in the stairwell. Otherwise, your upstairs hallway is relatively dark and it would also look better from the outside with a window.