I have been trying the same thing since a while; inquiring, 'Who am I?'. Not consistently though. But recently, got really serious about it. Thanks to the book Spiritual Warfare and some other factors maybe.
So, I realise that what I am looking for is not something I can imagine, perceive, think of or conceive of. And I keep on looking. And I don't find anything. The mind gets distracted. I bring it back. In a session of one hour, serious inquiry happens for maybe ten minutes.
So? Should I just keep looking and looking and looking?