Alteration zipper to corset?

Check with a seamstress for pricing on adding a corset back. That could help decide if it is okay to go with the dress. One bride's dress was altered to be too tight. She is considering boning and then mesh insets on the sides. You might be able to do insets and a corset back, if, hopefully, it does not cost too much.

I agree with the above comment - definitely look into pricing on that alteration and also look at what the dress would cost to buy new in your size. Alterations are expensive and ordering in your size may be cheaper! To give you a ball park, I had a seamstress shorten my dress, line the bodice, make some adjustments to the boob area, and add a bustle. That cost me about $700 in a low income area and with a seamstress who does this as a hobby out of her home lol

Definitely take your pictures into a local seamstress who specializes in wedding/prom dresses, NOT just a cheap seamstress. You need someone who knows what they're doing. Typically 2 sizes up or down can be accommodated, & a corset back is usually a really easy job. There is a piece that be snapped into place to cover the skin for modesty, appropriately named a "modesty panel". If you prefer to leave it out & show off a little skin, that's always an option too! The dress is very pretty but do see what can be done before taking a leap of faith.