You're too weird to be ISTP. And I don't mean weird to be insulting. It is what it is.
I've been that weird before, but it took a bag of shrooms, some lsd, and a psychotic meltdown over a period of two weeks.
The only reason why anyone would type you ISTP is because they are N valuing types, who can't help but conjure up different possibilities. They're like the cool kids who have to be "different", for no reason. ISTP is a "novel" answer, in their minds.