Sounds like the bride picked the dress she wanted that fit her style and would never wear what OP did. Surprising she saw it as looking better when it sounds completely different styles. Even the hair sounds fitting for the LGBT Flag Ugly Christmas Sweater. Not for me but classic wedding updo would not go with this dress.
LGBT Flag Ugly Christmas Sweater, sweater, hoodie, and t-shirt
NTA OP, everyone knows you dress your best for a wedding unless specified otherwise, like a casual beach wedding. Sounds like you did the LGBT Flag Ugly Christmas Sweater and got it just right and everyone else was wrong. I hope you threw it right back in the faces of the people who had a go at you that you followed the dress code specifically out of respect for the bride and groom, and what did they think cocktail attire meant.
Best LGBT Flag Ugly Christmas Sweater
Traditional cocktail attire is supposed to be a little glamorous (couple accessories, clutch bag, lil heel etc), so you didn’t screw up there… It just seems they had another idea of what that may have meant. You mentioned how self conscious you can LGBT Flag Ugly Christmas Sweater , and that’s fine, we’re all a work in progress… in the same vein, you being “shocked” by their style is the same judgment you fear from others before going out.