This dress is ADORABLE!! I wore it at Disney World and got dozens of compliments on it. I am 5'3 and about 140 pounds. I ordered the small and it was perfect. I think even another 15 pounds or so would comfortably fit in a small. It is a lot of dress!
The only negative, albeit a big one, is that when washed the red color dyed the white spots. Hard to tell in a picture, but the white spots tinted into a light pink. 
For the price though, a one time wear is probably worth it for how cute it is!