Identity is always in process.  You can say to people that “this…is who I am.”  You can describe who you are – at that moment, at that point in the process, but “Who I Am” is always in process.  In fact, tomorrow you will be different.  Your identity will be something that you invest or divest in.

Who I am – is possible to describe, but it will not be the same.  Who you are changes.  “Who I am” will be what will be engraved on your grave stone.  Until then, it means who you are at that moment when you said it.