Bringing the bottom in instead wouldn't have done a thing, the cut was too high up into the curve of the window, that is all there is too it.
Hotwheels, I am thinking at this point your best bet is simply to "create" the inner post you need to make the shape of the window correct. You have a few different ways to go, one is being a skilled surgeon and dice up the post above and below the cut bringing the inner line in more to make a nice line.
I am thinking to be more realistic, you take a flat piece of metal and you weld it on the inside of the pinch weld bringing it in where you need it (1). You trim this piece so you have a perfect line/curve. You then make templates from poster board (my favorite for templates) and make a triangle shaped template (2) that fills the outer portion of the pillar from the middle of the cut on the pillar over and in to cover the "poor" line that is now there.
Excuse the poor drawing, hopefully you can see what I am saying.