I think you need to do what it takes for the armor to fit you. Is that armor on you or a mannequin above? If you have cut that to your body size already, it looks like the two halves need to come together another 2 or 3 inches. Is that right?
Based on below, other screen shots and all the EIB/Centurion applications, the butt should line up around equal to the kidney. Some suits have that little check-out, some don't. So, if that picture above IS you, then you'll possibly need to cut an awful lot more off otherwise the butt will end up sticking out past your stomach. As Bryan said, leaving a bit of fat to play with wouldn't hurt. I haven't got that far yet, so that is only my opinion based on my research, not first hand knowledge.