I think it's not all that related to type. Any type can have low self-confidence... so I don't think it's very useful for working out your typing
Do you have trouble gathering the courage to do things, like approach a superior, or try a new skill? At a party, do you tend to stand in a corner and smile vaguely until someone approaches you, or do you easily converse with people you haven't had much interaction with before?
Something else I've noticed is that people don't tend to hate IEIs, and IEIs don't feel like anyone really hates them with a passion, whereas EIEs seem to have more detractors.
Another thing - I can lie in bed all day, just daydreaming and enjoying how warm and snuggly my bed is, but unefille can't imagine doing that. This might be temperament-related - do you have a stronger preference either way?
(These are all extreme examples, but it might indicate your tendencies.)
You could also post a video. Videos make VI a lot easier, and more reliable.