Let’s draft together the pattern of this vintage style dress.
Start from a basic dress with darts.
On both front and back, draw the new neckline and redraw the side seam reducing at the hem, then draw the bottom part with the slash lines for the flounce.
Draw also the underbust line. on back only, reshape the center reducing the dart.
On front only, widen the shoulder dart by 1cm at the neckline and redraw the waist dart making it more fitted at the underbust.
Reshape the sleeve to make it more fitted and draw a slash line at bottom.
Trace the separate pieces as you see here.
Space the flounce pieces and the two pieces of the sleeve.
This is the finished pattern: back bodice and skirt, two pieces for front bodices and front skirt, then redraw the flounce and the sleeve adding the new volume.