What you are going through is perfectly normal and has been called the "crisis of conversion." All of us who have truly changed religions at some point have gone through the very same thing.
On the topic of deities, I'm afraid you'll find that all gods have been in part shaped by culture. As finite and unenlightened beings we can't see, comprehend, or truly conceive of the divine as it truly is. All conceptions of this divinity, all gods and goddesses with names and faces, are just convenient symbols of the divine. The Triple Goddess is no more or less "made up" than Anubis, the Sky Father, YHVH, or Krishna.
Many pagans, including myself, believe in one divine force that rules all. The triple goddess, even the famed god/goddess is a tool to better define the specific energies being observed/used. I'm definitely not Christian, I can't bring myself to take a book re-written by man for centuries to contain authentic words or even testimonies... but I believe in the one true "god" :D
I've also been into Christianity before.. (well actually i still do attend their masses not because i do worship their god but just to show my respect out of the years I've been with him).. at first, i am also somewhat twisted with what am i going to do with my new religion (luciferianism) but then i just meditate and meditate and meditate and ask myself and let the universe show up new doors for me.. actually having been in such situations, yes you may find good information about something on books or everyone here but the truth is at the end of the day you are still the one who could answer the questions that goes on and off in you..
ps: hhmm.. this is just a personal experience.. ;)
I haven't looked into this much, but Sylvia Brown talks about a God and Goddess theology a lot in her books (though she interprets it as twin aspects of the single God). It sounds very similar to what you are looking for. Sh describes (this might be out of date) Father God as the Universe itself, a physical and relatively inactive deity. Mother God on the other hand, is basically Mother Nature, the active and cyclic deity. She also draws a relationship between Mother God and justice, though that relationship is very complex and abstract.
That's an interesting theory! I'm honestly not sure about this. I know I'm Pagan at this point, but I think I see all the deities as connecting to the Divine Source of God and Goddess. I like the idea of there being a God and Goddess that reproduced and the Goddess birthed existence. It makes more sense. In Christianity, it's like you believe in an asexual God, honestly! The Christian God couldn't have done all of this by himself. I see that all the beautiful ancient cultures longed for the Divine Source's existence (God and Goddess) and created (maybe even had experiences!) of or related to their specific deities.
I don't like the idea of following that concept if writers of the 20th century made up the Triple Goddess, though....
I am a christian and beleave in a one true God and even in the bible it mentions other beings that come to his kingdom to answer to him.. you read a good discription about it in Job. where even the devil has to answer to God.. basicly just like here on earth you had a High King and other smaller kings who would come to the high king and answer to him. To me that is basicly how the kingdoms of the other relm are run and take there order.. at least that is a basic outline.. none of us know all the detales of the other world and how it emcompasses our daily lives in full. but it is only natural for us to want to beleave in a higher being because that is how it was made.. i hope that you find what you are looking for.. it will always be that if you look you will find answers.. :)
Ultimately, whatever interpretation of the Divine Source you choose is fine. It is my opinion that "Supreme Being" actually wants to be interpreted multiple ways.