Dress from Modazehrada

I found a dress on their website that I absolutely love but am having a lot of trouble with the sizing. She told me their biggest size (58) is a US size 30, which is bigger than what I normally wear. I’m a US dress size 22. When I sent her my measurements, she said she thinks I would be a size much bigger than her biggest size. I am very conflicted. Has anyone in US ordered? What was sizing like? TIA!