I just think it might be a bit narrow for your arse.
My B17N is very comfy. It is level-ish (back rim to front nose, it dips in the middle). I didn't fiddle around with the angle before settling on its final position. It just went to the correct height, and bit of forward and back waggling and a quick 'looks level' with the eye.
But I am fairly skinny, so maybe my sit bones are closer together than yours? If it is your arse, rather than perineum that is hurting then I would have thought the width is the more likely culprit. What sort of build are you? Your name implies that you might have been better with the normal B17.