I stumbled upon the 'Please Understand Me' Keirsey book in a library, probably around 2000. I looked through everything, didn't at all think I was an F / relate to F descriptions (and back then, in earlier format mbti/big 5 tests, I never tested as F), and highly related to INTJ at the time.

AM I that? Oh who knows. Does it matter? Probably not (I wouldn't be an 'extreme' one anyway).