Does this corset make me look fat?

A corset is designed to make you look skinny but honestly it looks too big for you at the top, maybe you should invest in one a smaller size? A corset needs to fit and has no loose bits(unlike yours which looks loose at the top). Based on the one you are wearing it looks like your bust is too small for the size of the corset you are wearing therefore you would need to get a smaller size for your bust.