KSKshapeSeamless Body Shaper Open Bust Shapewear Tummy Slimmer Bodysuit for Women

So I’m usually a size 10 but according the size chart I’m an XXL with 33 inches 🤷🏻‍♀️ Help please!

do go a size up or down? I measure exactly 27 inches and normally wear a size 8 top and size 10 bottom

Do i have to go down one size in order to be a nice shape and keep everything flat??

I want to know how do you go to the loo once you have this devise on