Are you in love him or simply love the comfort of having him there? It would seem to be the later....don't be selfish, he deserves to be with someone who WANTS to be with him, let him go.
Do you think you pressured him into the engagement? That could be a reason for your anxiety and confusion. If you want to leave then leave. Who's stopping you? Don't let your thoughts alter your decisions Just do it, leave, don't ponder on it. It's just another excuse to stay. I've been there.
What is too much? It's ok to have standards. There are a few men out there who are willing you just have to be patient. The things we want come when we least expect it. Don't focus on it. It's not a matter of a perfect guy it's the principle of a guy being perfect for you.
You are just afraid of commitment. It could be that past relationships have got you down feeling skeptical or you are afraid that once you get married, he'll leave. I don't think you need a break. I think you either need to "stick it out" or leave. One of the two. If what you're worried about is so concerning, then you need to fix it or get out of the relationship, if you can't.