After carefully considering all your inputs and wishes regarding the space, I find that the proposed design best answers your needs and is within the given restrictions regarding installations and building structure.
I'll briefly talk through the proposal to explain some main points.
Apartment structure:
- open space lounge with kitchen and dining area
- three bedrooms with double beds
- two bathrooms
- storage space
Since you believe that the only vertical connection for the bathroom installation is at its current position I assumed it's in the area between the current kitchen and bathroom, and organized the spaces that need an outlet around that area which makes it more convenient and cost-effective when it comes to construction.
The open space area is facing the internal courtyard as you preferred and is directly accessed from the entrance of the apartment. This makes the apartment functionally divided into a day and night area. The day area consists of a lounge, a kitchen that is fully equipped, a dining area that can be extended when hosting a larger number of guests, and a bathroom that is accessed from this part of the apartment.
This gives you a larger living area than you previously had, it keeps the balcony access from the living area and also provides the kitchen with natural light and ventilation while connecting it to the same vertical outlet from the bathroom on the other side of the shared wall.
The night area consists of three bedrooms and a bathroom.
Since the wall dividing the apartment horizontally is structural and it was not possible to make new openings in it, I decided the best solution is to move the corridor to the other side of that wall making the two large rooms slightly smaller while maintaining their functionality and gaining an additional bathroom next to the original position of the bathroom and kitchen.
This design solution gives you a more intimate corridor not visible from the living area of the apartment where you more often have guests. The corridor connects all three bedrooms and a bathroom. With this being said, it is also designed in a way that you could enclose the bedroom facing the internal courtyard and the bathroom and have the bathroom be an en-suite bathroom for that bedroom and have the other two bedrooms share the second bathroom since it is close to them as well. But this is up to your preference and does not affect the design in any way.
Both bathrooms are equipped with a shower, toilet, bidet, and sink. As one of the bathrooms has a larger sink area the space could be used for a washing machine if preferred. Another option for the washing machine is to place it in the storage space in the corridor if possible and use the storage space as a laundry area with additional storage for cleaning supplies and bedding.
For the room in the attic, I've arranged both the option as a gym and as a small home cinema space, and it is up to your preference and needs to decide between the two.
As you did not post any references regarding style, color, or other preferences regarding the aesthetics of the design, I did some renderings using predominantly neutral colors such are white, black, and natural stone and wood just to give you a better idea of what the new spatial organization would look and feel like. The style and materials could be changed according to your design preferences later if this is a direction you would like to take.
I hope I've managed to explain the main points of the design, and if you have any further questions feel free to contact me.
