Wedding dress alterations.?

I need to get my wedding dress altered i got it and since then Ive developed a problem that apparently my have gotta about an inch and a half bigger which makes wearing the dress very uncomfortable. It needs something done and im not sure if i should see about getting it let out if you can even do that or if theres something i can wear under it to squish me into it or if theres a way i could get the zipper cut to a point and then make it tie rest of the way up or something. Any advice from someone who has done something like this or knows what needs done would be greatly appreciated.