I’m 5’4, 100lbs, and ordered the XS. The straps, no matter how I positioned and adjusted them, kept falling off my shoulders... I am slightly muscular in build, but still pretty petite. Given that the suit did not stay on well at all on land, I didn’t want to test it out in the water, and will return it. Am very disappointed as I really wanted the suit to work, as it is beautiful!! The fabric is very soft and thick without being too warm. The straps are a slightly different color than the suit (white, whereas the suit is creme/ivory).