I am a size 6 but I ordered a size 10 because of my large breasts (34G) and round hips.  I didn't want my breasts spilling out of the top and did not want my behind hanging out.  The bottom covers my round behind nicely.  I am glad I went up to the size 10  because I also did not want the bathing suit to hug too tightly which can cause issues especially if you are in a wet suit for an extended amount of time.  My body needs to breathe.  Also, I love the lace pattern and how it shows some skin but not too much... great for moms with stomach stretch marks who miss those two piece bathing suits.  There were two types of straps provided.  I prefer the thicker straps for my large breasts.  Its also much more comfortable on my shoulders.