You spent an hour stressing about the haircut and two people noticed. Most people are busy being themselves.

You are the only person watching you all day. Everybody else is inside their own head, managing their own appearance and worries, and they get a passing glance at yours. The feeling of being examined comes from the hour you spent in the mirror rather than from the room. Most of the audience you are imagining is you.

Count, next time: notice how many people actually mention the thing you were dreading being seen. Usually it is one or two and they are kind about it. Knowing the real number makes the next haircut, outfit or spot much cheaper to live through.