lizatola - If this is your fear "That maybe I'm settling for a comfortable relationship when I may want more." What more do you think you might want? Do you have a gut feeling that you don't love him? How long were you dating before living together? From the way you describe your relationship, it sounds like this is a very considerate man.
I literally laughed out loud about this - "He's a thinker and he processes EVERYTHING internally before he makes a decision. He doesn't trust emotions even if he has them; it's like he has to rationalize his feelings and think about them before he knows exactly what they are." I completely understand that and it is foreign to me that everyone doesn't do that. Does that bother you? Why do you think you're more invested than he is?
I'm asking those questions because I am trying to understand what exactly you are afraid of. Maybe there is more than what you have stated your fears are?