Very light material fit flare dress

This is one of my most favorite dresses in the world however I cannot fit it anymore it will not fit a 12 it will fit between 8and 10 perfectly if you have a small waist or fairly small and you can have wide hips.. Well you don’t have to have wide hips but it complements the dress I can’t even zip it up because I’ve gained so much weight but when I was a size 10 it was perfect..It’s in perfect condition