We definitely need a basement, we are sure about that.
You are planning too small.
I see dimensions that are too small for practical use.
But first of all, I have to congratulate you on the graph paper – it’s still the best and most effective way to plan. Most people shy away from the several-euro price but spend 50 on software they can’t operate.
In general: 2cm of plaster on every wall, additionally tiles in the bathrooms, baseboards in the rooms, furniture placed 5 cm in front of a wall. Variations in stone and masonry—all that should be factored in by a layperson. That means you should plan more into your sketch than exactly edge to edge.
If you as an amateur planner plan with a precision of 10cm, there can be tight spots. For example here: guest WC shower. You have just under 80 cm drawn with a sharp pencil. If a general contractor now takes your idea 1:1, then you barely have space for a 70 cm shower. If you think a 1-meter shower is too big, then at least draw it in anyway, even if you only plan 80. Then you come to a 90 cm space. The remaining 10 cm benefits the room. The size of the washbasin is only just okay for hand washing.
Kitchen with a 60 cm row. No cabinet stands on a groove on the plastered wall, a countertop is often 62 cm deep, so better take 70 for the sketch. Two 60 cm cabinets need 150 cm in width...
A wardrobe should also accommodate hangers, so plan it like a wardrobe with a 60 cm depth.
The staircase with 4 meters has a good length for planning.
I would turn it (as you have already noted) and have it start at the front from both sides, so 2x winding.
Try drawing your furniture in the living room – with a width of 3.30 and open to the front, I can’t see a really nice room there.
Leave the beam to the architect to plan. With narrow houses you do not always need one.
Instead of a seating window, just plan large window fronts that allow a place for a variable armchair.
Basically, the open-plan room is very large, which I personally like, but in my opinion it is not well shaped. There is little retreat space. Even at Tupperware parties, card evenings or football games with friends/guests, the other residents have no possibility to withdraw from the event bustle.
On the upper floor: the wall in front of the staircase exit is awkward. That’s why my suggestion with the 90-degree turn.
In the meantime, we have had the idea to open up the rooms on the upper floor all the way up to the roof, if possible also extending it over the hallway, and thus create a second level in the children’s room, which would still result in a spacious children’s room despite the small room footprint... but these are all just ideas at the moment...
Personally, I wouldn’t do that with a steep roof pitch. But that’s up to you. The room can quickly lose atmosphere instead of gaining it.
I find the sleeping area very unfortunate with the wardrobe. It’s better to place the wardrobe behind the door. For that you then plan the room accordingly with about 70 cm behind the door.
The dimensions advice also applies here in the bathroom. Besides that, with four people, you should have access to two wash areas. Also, the bathroom could use 1-2 sqm more.
Could the storage room protrude beyond?
Of course! The problem with the morning sun is only that you either experience it in the office, while shopping, oversleep it, or enjoy it on the terrace.
I still see a lot of potential in the planning, possibly one meter longer or one meter shorter and half a meter wider.
The plot is simply short and not generous... so you can well plan the terrace by the dense hedge at the sidewalk... or put the kitchen with terrace on the west side.
I would probably try to move the house forward and the carport much further back...