Plaid Puff Sleeve Midi Dress

I bought my usual size 6 per the sizing guide. The lower portion of the dress is very nice with a fun swing to it. But from the waist up it’s cut very oddly. It’s gappy and seems proportioned for several sizes bigger. I’m short waisted, so that might be part of the issue, but the bust area is enormous. No amount of adjusting the waistline up (is it trying to be empire style?) or down resulted in a fit that made any sense across chest and shoulders.