I'm the same and did not discover this until about the 5th time I took the Myers-Briggs Personality Test. My initial tests had me almost exactly between extroversion and introversion.
On my last test, the facilitator explained the energy/stress aspect with a number of examples like your dinner party. She also mentioned people are naturally one or the other, not 50/50.
I realized that my natural inclination was introversion. I believe that what I perceived as my extroverted side was learned through a social upbringing to engage others, which is beneficial. There are a number of social/extroverted things that I sincerely enjoy but I walk away exhausted.
On my last test, the facilitator explained the energy/stress aspect with a number of examples like your dinner party. She also mentioned people are naturally one or the other, not 50/50.
I realized that my natural inclination was introversion. I believe that what I perceived as my extroverted side was learned through a social upbringing to engage others, which is beneficial. There are a number of social/extroverted things that I sincerely enjoy but I walk away exhausted.