Hello,
I would like to explain the concept of my design. Your apartment is long and narrow with windows on only one side and because of that it is inevitable that it has long hallway. Instead of trying to make a hallway smaller I decided to make it larger and useful. The idea is that main rooms : living, miscellaneous, bathroom and bedroom are all on one side with windows and on the other side is the kitchen which continues to the hallway (that becomes large closet space by adding built-in closets). The hallway ends with walk-in wardrobe from which you enter the bedroom.
That way you are able to get everything that you wanted in a 55 sqm apartment.