I am so sorry for your loss. You should not be faulting yourself in any way for any deficiencies you think there were in your dad's last hours. He was home, with you, being cared for by one he loved surrounded by the people he loved. He got to spend the last days and weeks of his life talking about things that were important to him. That is a wonderful thing to have done for him, and you should stop second-guessing yourself. The end is seldom pretty, and however much you love someone, you really can't make it so.
My sister, 53, died of colon cancer a year ago, and I try to take comfort in the fact that we were able to keep her home, and see her out with love. But believe me, it wasn't pretty.
Please be easier on yourself.