Same here. As I was looking at the picture, tried to fix my posture, and then read your post. lol
I do need to work on my posture, but my desk is a little awkward and small so I have to sit in an odd fashion at it.
My ribs actually are starting to hurt more than my back or anything else, also my chair isn't that great either. I need a replacement whenever I can scrounge up the money to get a new one.