How to design a 12 square meter bedroom (square) to make the most effective use of space?

Your bedroom is quite wide (3490), but the depth is too short (3600), so it is square.

Now the picture is basically ok.

Jane: The TV cabinet is cancelled. After crossing 850 from the door, put a kitchen cabinet with five buckets, put a long writing desk on the south wall next to this cabinet, and set an open bookcase (you can sit hanging) on the countertop near the south wall. There is a drawer under the countertop and the rest are open. This cabinet can be customized or made on site, but the countertop must be customized by the manufacturer.

There is an LCD TV hanging above the desk (opposite the bed). The top of the machine is under the table.

Ah, it's a bit like the layout of an express hotel, ha. But it is also the most reasonable plan.

This scheme makes full use of the width of the bay.