It is extremely important to measure properly, if you take your own measurements, before using the designer's size chart. With proper measurements, we can help you in choosing a size, but we cannot choose the size for you. Normal dress sizes do not apply in Bridal Wear, as each designer has their own size chart and makes their dresses to those specifications.
Size is also subjective according to the individual.
Some may be more comfortable with a dress that is tighter in certain areas than others. Please remember, should alterations be needed, it is easier to take a dress in than let it out. If you are not sure of your measurements, it may be best to go to a bridal shop or tailor and be measured by a professional. Measure at the widest part of the back straight across the top of the bust. Do not measure under the bust line.