Difficult to be authentic around others?

Maybe you haven't defined what is ''to be authentic''.

I find this word ''authentic '' just hard to understand to be perfectly honest with you.

So let's look for a definition - google authentic

Well after reading the definition, it does not help really.

Maybe worth diving in existentialist philosophy to recognise authenticity as the emotionally appropriate, significant, purposive and responsible mode of human life.

Accepting that you do not know what is to be authentic is probably a step to salvation. You can stop pretending that you know everything and just accept that you are still a baby that came out of the womb exploring what is the world about. You are just an inquisitive mind amongst many others bound in an imperfect body and an imperfect world. Then, you can relax around others, they are the same as you anyway, crazy kids...