That must have taken you by surprise. Rather than asking “Who am I?” have you ever wondered “Who you really are?” in the eyes of others. Who you are in your own eyes is usually quite different from the way other people view you
You are the only person who spends the most time with yourself which would probably indicate that you know yourself best. But there is an issue here as our assessment of ourselves sometimes can be quite erroneous. We may have wrong ideas, wrong biases and wrong judgments on which we base our own image of ourselves.
This does not necessarily mean that the assessment others have of us will be right. In some cases it may be more correct than our own view in others it may not.
So how do others see us? Other’s view of us is based on the interactions that we have them. In each interaction people see us through a small window. Each subsequent interaction is another window. Typically what happens is that people tend to interpolate and average out your personality between these windows and arrive at what they think is your personality. For e.g. if several of your meetings with an recent acquaintance of yours shows up your humorous side then it is quite natural the other person will assume that you are generally a fun guy to be with. If you appear irritated and testy during your brief interactions the other person will form an opinion that you are generally a short tempered person.
So while in your own mind these behaviors of yours may really be temporary the other person view of you will be based on these windows into your personality rather than who you really are. So don’t be surprised if somebody has a completely different idea about you as you have of yourself.
This is particularly important in the professional world. Make sure you keep sending those “Hello” messages to your manager and your colleagues. This is also another reason to network and interact more often with your friends and colleagues so that your perception of yourself and the perception others have of you are in sync.