I find your project quite interesting, as it somewhat resembles my "project that didn't happen."
why should I have the bedroom on the ground floor if I have enough space upstairs?
Well, I can think of many reasons besides "that would, among other things, loosen up the narrowness." Your plot is very narrow, which already places high demands on the floor plan. At the same time, you're trying to cram all wishes, ideas, current trends, etc. into your floor plan, which, in my opinion, would suit a square house better.
When planning, one should consider a long-term usage concept. You yourself say you want to move into the attic at some point. Well, I would prefer to have the bedroom on the ground floor with an en suite bathroom. I'll compare it to my "project that didn’t happen": try searching Google Images for "Zweifamilienhaus Xanten," there is an identical house (unfortunately no floor plan to see, which I can send you by email (expert report) if desired) "to be completed." It's a detached house, but they also planned one side without windows. As the name suggests, it was planned as a two-family house, with one apartment downstairs and one upstairs. I think you can apply that to your project too: build a two-family house, upstairs the open living room as a play area for the kids, of course no kitchen upstairs, own bathroom for the kids, etc. This would now have the advantage that the house "fits" over the years of use, meaning the kids grow up and have different needs, etc. Once the kids are out of the house, you could rent out the upstairs and the parents remain downstairs, returning to the bedroom on the ground floor.
Your plot is very narrow (the project that didn’t happen had a much larger plot). Is the neighboring house already built or can it still be planned for? With such a narrow plot, in my opinion, it would make sense to set the house further back to place two parking spaces (or carport/garage) in the front. If that no longer works: or you lay the garage/carport/parking space further behind the house. That would have the disadvantage that you need to build the driveway, but you would have enough room for a side entrance. I would not slap a garage or carport onto the house, as you would then be missing windows again...
Your wish for a large open living/dining/kitchen area is, in my opinion, somewhat oversized. Here we are back at the bedroom on the ground floor. That would reduce the space in this area, which would actually be good for it. Take a look at the attached picture. That is the view into the living/dining/kitchen area with lots of light. Because of the projected dining area, they could install even more windows (light). I actually found that the best part of the building. I didn't have the feeling that it was too small there. If I imagine the building that I actually visited with your floor plan (I look terribly long from the entrance all the way through to the window front of the living room; the windows would look smaller optically and the ceiling would feel very dominant and oppressive). The conclusion would be: entrance to the side, no other way around it...
