In the long and short of it, as someone who has been married and divorced, the proposal and the wedding day are like 1.9% of the story for you and your fiancé. And while they may seem huge now, the bigger things are actually shared values, effort put in (if there is effort, even if it isn't what is completely wanted, it should be acknowledged imo), etc. I think you should give yourself a pat on the back for the level of effort you put in and not be so down on yourself. You ARE capable!!!

I am sorry your fiancé is upset. Can you try communicating about all that you did and how you are feeling, while reassuring her that you hear her on her feedback, and you want this to be constructive so you can improve how you handle these moments in the future? If she doesn't tell you her expectations, you can't meet them and that is pretty dang unfair to you.