This is a preowned Lillian West, style 6422. It has been worn once. Designer size is 22, my dress size is 16. The only alterations I had done was to hem the bottom a tiny bit shorter (I'm 5'8" so it's still plenty long as you can see from the photos) and added some applique to the sides of the back of the dress to disguise a lil plumpness in those areas! =)
This can totally be altered so don't be shy about the current size. It can be hemmed farther, the waist can be taken in, and the top can be altered as well.