I don't get it...I must be long in the leg then? or long in something....I never thought it was my torso though.

Anyways....a stillwater is a traditional kilt, made to be worn higher than a UK for sure.
I have a stillwater and I'm only about 5'8" and I can wear it just fine. At 5'11" i'd think you'd have no problem at all.
Can you by any chance snap a couple of pics and let us take a look. what to you feels like 3.5 inches over your navel, may actually look about right.