I have this same dress in Medium and color grey. The Medium is a bit too loose on top and I thought the Small would fit better. This is not the case at all.
The fabric is too heavy for the length of the dress and pulls the top part so far down it doesn't look good anymore. While at first it seemed like the Small exactly the same size as the Medium, it now even seems as if it's bigger. Doesn't make any sense.

Since I'm at an APO, sending it back for a refund via USPS would be too costly so I'll have to spend even more money on getting it altered in the end.
Not pleased at all.