I've always pretty consistently tested as
INFJ:
They are, in fact, sometimes mistaken for extroverts because they appear so outgoing and are so genuinely interested in people -- a product of the Feeling function they most readily show to the world. On the contrary, INFJs are true introverts, who can only be emotionally intimate and fulfilled with a chosen few from among their long-term friends, family, or obvious "soul mates."
I am constantly trying to explain this to people who don't understand why I don't
like working in client- or customer-facing positions even though I consistently get praised on performance appraisals for my abilities in this area. They don't "get" why I go home exhausted after spending all day doing it...