Alex,
What I get from the dream is there is a transition {hall} taking place. The fact you attended your sisters graduation probably stimulated the use of these symbols because both of you are moving on to other things in life. Your higher self {father} has had indecision {sitting} but that has come full turn {number 10} when it comes to Lady P {she was the thing you once felt the higher cause in your life}. She has become less a presence in your life and that is good {beautiful garment}. Your higher aspects to do with the feminine is helping you assert your true self and helping you to move forward.
The dream does seem to be saying you are making progress. the above interpretation would probably fit with your feelings toward Lady P. In a deeper sense Lady P would represent your anima/feminine aspects. It may indicate you are overcoming early life influences that prompted your obsession on the feminine to begin with. What characteristics does your father possess that you may have been imitating but now you are growing out of?