This may seem “shallow,” but I think it matters a great deal - do you take time to take care of yourself? I am no great beauty, but I feel very different about myself when my body and hair are washed, my nails are trimmed, my teeth are brushed, I wear clothes that fit and flatter my body type, and put on a touch of makeup. When it’s a roll out of bed and wear sweatpants kind of day, I tend to feel very blah about myself. Most people are average looking, but average-all-cleaned-up looks a lot better than average-not-caring. (And weddings tend to bring out the big guns for clothes, hair, and makeup. If you’ve got a professional photographer, he or she knows how to do flattering shots, too.)
If you struggle with self-esteem, and especially if you have for a long time and not been to counseling, I’d highly recommend that you try it.
And what does your fiance say? If you want him to tell you you look nice, ask him to! Some people aren’t big with words and may not know how much it means to those of us who are.