Corner reliefs and flanges not equal.

I just tried today to make a basic column using the Sheet Metal tools and I get some ugly results. Seems that the flanges are not equal and the corner reliefs are bigger in one side than into the other of the same corner. Also I need only 1mm between the flanges and I can't find any option to decrease the size between flanges. How to properly made a sheet metal part like this starting from a box? I attached my .dwg experiment for better understanding.

How I can bend and create a new flange in one side at "junction_5"? I need some extra material that will go under the other side for soldering.