You sound like you have similar measurements to me - The best thing to do with bodyline sizes is to measure yourself accurately.
Get your bust, waist and hip sizes and write them down, and look very carefully at the measurements listed on the clothing you're looking at. Bodyline sizes can vary alot in their measurements, depending on shirring etc.
I always make sure the measurements listed are a few CM bigger than my own so I know it will be a comfortable fit :) Hope that helps!