My prom dress needs to be bigger (in the chest area) and there's a zipper on the side.. any suggestions?
Take it to a seamstress to let out the hem. Yes, prom dresses usually have an inch or two of extra fabric in the hems exactly for this purpose.
if you sew..you could open a seam on both sides and add some material..
You probably need to let out the side seams a little to fix the chest area. However, this needs to be done professionally to avoid ruining the dress. You should probably have a seamstress make the alterations for you.