House renovation problems with the attic / mezzanine regulation

What do you even mean by "full storey"? - do you want to put a second straight-wall storey plus a living-area pitched roof storey on top of a straight-wall storey (plus currently a storage-room pitched roof storey), or even a setback and a setback-setback storey? - how much height do a. the development plan and b. the clearance areas actually allow?

The HBO states that the attic or top floor may have a height of 2.30m and cover a maximum of 3/4 of the area of the floor below.
By area, you mean the GFA, right?

It’s purely about the question of whether the balcony or loggia counts towards the floor area or not because of the 3/4 rule.

Let's be honest: I was not an architecture student, but such knowledge is basic knowledge for me when I am dealing with house construction only because I am interested or want to have some influence on the architect in my own house planning.
In this respect, you should rather do your homework than ask a layperson forum. No offense!