Retro jade ModCloth dress

This is a great dress! I love it. I wore it to my friend's wedding and then maybe another time or two? It's in perfect condition. I got compliments on it every time I wore it. I gained a little bit of weight and now the rib cage area doesn't fit. I hate to say it, but I guess the size tag came off! I don't actually know what size it is, but I think it's an extra small. I think it could fit as a small as long as your chest is not too large. I am 5'7, currently 140lbs, B cup, almost C cup.