This question is one (if not) the most worthy of posing oneself. Even the fact that we are able to ask this question should amaze us.

As to who you are, you can think about it in different levels of depth:
-you are first a conscious being and everything else is outside your consciousness
-you are one who is looking for happiness and avoiding suffering
-you are one who is looking for various meanings to find
-you are the goals that you have proposed for yourself
-you are the judgments and axioms that you have said yes to
-you are the thoughts that you cultivate
-you are the sensory inputs that you participate in