Firstly, this is a great piece. Thank you for writing it.
Secondly, everyone grieves differently. I personally couldn't care less who judges me, but like you I didn't cry at my father's funeral. Why? Because I was far more concerned about my mother. My own grief went on hold. It always does (a similar thing occurred when my father-in-law died - I was far more concerned about my wife).
Later I grieved for both of these wonderful fathers, privately. I don't do public grief. What's more, I have outsourced my feelings to novels and films. So a few months down the line after my father's death, after watching The Tree of Life for the second time, and also Departures, I wept like an idiot.