I'm 5 10/11 ish and the back fits about right, you may have a longer torso but it still doesn't look right. Hard to tell but you may well have the butt plate too low.
I started by attaching the kidney to the ab plate, then added the but plate. I then attached the chest to the back plate. This means you have a top half and a bottom half that you can put into place and see exactly where your gaps are if any. Don't be afraid to shove the butt/code up as far as it will go, you sort of need to to align everything.