She sounds like someone who is pretty fussy about things. When a fusspot hooks up with someone who may have a more relaxed idea of how to go about things, the fusspot is going to be chronically complaining. I'm a fusspot and my s/o is not. If I want something done exactly a certain way, then I had better do it myself. But I don't denigrate his every effort.

Neither you nor your fiancee can remake yourselves into who you are not. You're not obligated to become her obedient servant. It's okay for her to prefer to do certain things herself. It's not right for her to be insulting towards you on a regular basis.

Instead of thinking, "She makes me feel like I'm nothing." start saying "She makes me feel like she thinks I'm nothing." You can't really put on her how you feel about you. You can decide that for yourself. But you can legitimately conclude that maybe she has a low opinion of you. And you can tell her that: "You seem to not think much of me. I wonder why you want me to be here. And I wonder if maybe I should leave."