Wall construction including insulation stud frame construction

Hi, I have a small construction project here and would like to know how the wall structure should be. It's about a (future) apartment, approx. 60 m2 with a shed roof. Below that is a basement. So far, from outside to inside: glazed profiled wood, 30 mm battens, 12 mm OSB boards, 160 mm wooden studs. Now I wonder how I should proceed further inward to eventually get to the plasterboard. That means insulation (most logically probably 160 mm between the studs, right?) Where should the vapor barrier or rather vapor retarder go? Should I additionally build stud walls and insulate again in the space between?! Thank you very much

The wall construction seems a bit "thin" to me. My wall construction in my planned house is as follows from outside to inside:
Plaster
120mm wood fiber insulation board
180mm timber frame (blown out with wood fiber)
12.5mm OSB board
70mm cross battens and soft wood fiber insulation boards in between
12.5mm gypsum fiber boards

In my case, the OSB board (airtight glued) is the vapor barrier, since it is more vapor-open towards the outside. And the cables etc. go between the cross battens. It is basically the installation level. This way you don’t have to penetrate the vapor barrier with installations.
Inside must definitely be more vapor-tight than outside.

Will it be a small house or an extension for you, or how should one imagine it? Depending on how well you want to insulate, the wall construction is thicker. You could also place the OSB board inside and a wood fiber insulation board outside. This way you would be vapor-open to the outside.

Hi and thanks first of all for the reply.

So what I wrote is already there. It is an unused outbuilding, freestanding. So more like a small house. The facade is already finished, simply so that there isn’t such an eyesore on the property for so long. Insulation is now only possible from the inside. Only on one wall are 40 mm Styrodur boards additionally attached on the outside, as this was plastered on the outside and did not receive wood cladding.
Now I don’t actually know how thick the insulation should be at all – whether 160mm is enough... by the way, everything is being done by myself.
I also wanted to incorporate the installation level for water and electricity. I was thinking of insulating the studs, attaching a vapor barrier with battens on it, then counter-battens crosswise and double drywall on top. But whether that is correct and/or reasonable – no idea.