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.