My dear sweet soul, I hear in your words your own prayer, a prayer for an answer to your doubts about prayer, a seeking of the positive in a universe that ends for all of us in death.
I cannot answer your prayer but only tell you of my feelings about this same dilemma:
I used to pray that God would show me that he existed and He never did until the moment when the last of my faith was extinguished, when I surrendered to the hopelessness I felt knowing that He does not exist for me but that my own will, my own desire for the good couldn't in hopelessness be taken from me, that the love I sought out there in some King of the Universe was all right there inside of me.
It was possible then for me to understand things differently than I did before, this for example:
Our Father, which art in heaven,
Hallowed be thy Name.
Thy Kingdom come.
Thy will be done in earth,
As it is in heaven.
The Kingdom of Heaven is here for the person who prays that his will is the Will of God and that what he prays for is what God wills.
Everything is attitude and I believe the perfect attitude can be had by those who have no prayers for the self but pray that the Will of God is done on earth as it is in heaven. To experience such surrender and trust is to love. I wish you much love from someone who believes that the Love of God finds its way into the world from inside you, that love is God's Will.