Actually, MBTI recognizes each person is both extrovert and introvert, both thinker and feeler and both intuitive and sensing. You do have to dive into the whole world of how each type is broken down into functions.
So the INFJ, for instance, has the dominant traits of introverted intuition, extroverted feeling, introverted thinking and extroverted sensing. Those functions are used most.
The shadow side is the inverse of the favored functions. This is where the person can retreat to when under large amounts of stress, grief, etc.
I’m not saying that it’s accurate, I’m merely pointing out that the notion of types being all introverted or all feeling, is not something MBTI preaches.