How the wedding dress fits determines if you look good in the dress or not.
The most common mistake soon-to-be brides make: they choose a dress based on a picture and stick with their choice. Until you have tried on the dress and few other dresses, keep your options open. That perfect looking dress might not be perfect on you. (Not to mention you should never trust pictures anyways).
Dresses from different brands have different fit, try few bridal gowns from at least two different brands before making up your mind.