NWT Lilly Pulitzer Tansy dress in First Impression

NWT Tansy dress in poolside blue first impressions. So, so cute and I absolutely love this but it just doesn’t fit me - runs small in my opinion - more like a 6/8. Beyond gorgeous dress!!!! Has the tiniest mark that I have not tried to treat (pictured). It’s not noticeable but I want to be extra picky and upfront.