I ordered a dress online that was only $50 to find.... it didn't fit right.....

It is my dream dress and it was in the largest size available. Even if I lose a bunch of weight, it will still be too small in the bust. A few people told me it could be changed to a corset-back and have a panel put in it to allow the 3-4 inches extra room I need. (I think it was that much, it just wouldn't zip past the base of my bra.) I also thought of wearing a corset, but I will be dressing myself. Help???? I don't hae much leway with funding to buy a new one......