There is a conflict of objectives: right now you are a 'large family' with 3 children and many guests - meaning you need a correspondingly large kitchen, wardrobe, dining & living area.
If the unit is supposed to be a 3.5-room apartment at some point, the requirements are quite different - the apartment is then designed for 1 to max. 3 people. The importance of bedrooms with wardrobes is then higher, the sleeping area should also be somewhat more separated, the kitchen & wardrobe significantly smaller, etc.
Swiss army knives that do everything still have not been invented.