Savannah Drawstring One Piece

It really breaks my heart because the quality feel and pattern are great but the sizing is not what is described. I ordered a 3XL following the size description and model reference, was so excited to get it in, and it would not reach my whole torso length. The fabric was so stretched out when I put it on you couldn’t even see that. It was the dark beautiful blue had my sister who’s a true medium come over put it on and it fits her like a glove…? Just confuse on how it’s a XXXL and is fitting a medium to a tea.