Help someone please. I have been invited to a black tie ball at Christmas but just don't know what to wear and can't decide what is right the etiquette ie full length or cocktail dress. Part of me would love to go for a full length dress but I don't want to look over dressed. I am 5ft 6 size 10 but self conscious about my stomach and tops of my arms. I love navy but would consider most colours and have up to about £150 to spend. Shoes are probably my biggest problem, I don't much like and can't walk in heels. I have very narrow feet and a lot of shoes hurt me. When I find a comfy pair I buy in bulk but don't really have much suitable in my current wardrobe. Any advice welcome, I don't often get a lovely night out like this and I want to feel the part.