I was wondering, do any other INFPs have the feeling that they are perfectly chill when alone, but when close friends show up, they turn boisterous and rude? Like a mask and a suit had suddenly been placed on them, and they were asked to do the chicken dance?
When I was younger, I used to have something similar happen when I was on a date. I wasn't boisterous and rude, exactly, but I was trying hard to be "wild". It was so important in the eighties hair band days to be "wild". I think it's natural to go through more identity confusion when you're young because you're experimenting with roles and identities. Don't beat yourself up over it.
People used to tell me to "be myself". But the problem was I didn't know what "myself" was, because I felt like I consisted of infinite potential. I was very adaptable and chameleon-like. The opposite of the people you meet in the workplace who are King or Queen of the Rut. They are so certain all the time, so full of confidence in everything including their own role and identity, because they have chosen to be a simple person living a simple life, just so that they can feel certain all the time of what to do, what to say, what to think and how to be.
The best advice I can give you is to take every opportunity, while you are young and not trapped, to seek out situations and people that are more congenial to you. Try not to waste a lot of time trying to fit in with people or places that are not congenial. That is, if you have that freedom and that luxury. If you're still in high school, you may not, but soon, you probably will.