I agree that you should just work on you. Not saying you got problems, but relationships complicate things and some people will go from one to the other quickly to have someone in their life. The fact that you have a dilemma between the three should indicate that perhaps you should just slow everything down. i would certainly figure out what my stance is with my kid and I know each state is different, but I had a pretty easy divorce and split custody right down the middle with my ex. She gets to be a pain to deal with, but for the sake of ease, I don't make waves and I get my kids three days on three days off. As much as I love them, the Mother and I both get time to do grown up stuff. I imagine in the future, my daughters will make a decision on who they want to live with for the majority, but for now, I am a big part in their lives and that is what I wanted. Every other weekend wouldn't work for me, and I layed down the law that the only cuss words we could say to each other through the whole event would be "full custody" from either side!
Sorry that she is not mature enough to see that there can be a fair split and if you are majoring in Psychology, then you must know that there is a separate root fear somewhere in her decision. No physical custody even if you are living together and you are supposed to work this out how?? I would figure out where I stand with her and what role I would be playing in my child's life (whether court appointed or not) before considering the complications (and let's not kid ourselves, even the best ones are complicated) of a relationship. Hope it all works out though!