Now, to get the high-low effect, I did it the same way as the tulle layers on the Strawberry Shortcake Ballgown I made a few years ago. Fold the fabric so that it is off-center. Measuring from the corner, the shorter side should be the length you want the front to be PLUS the radius of your waist. For Halley's dress, it was 16" + 4" for a total of 20" You can see that on the left edge of the picture. The longer edge that sticks out underneath is the back and should measure the length of the back plus the waist radius, or 28" for this dress.
Cut your waist radius out. This is where you need to be precise. I used my exact 3 7/8" to make an arc.
I didn't take a picture, but this dress also needed a lining. It all depends on your fabric, but the sheets I used were white and thin. I didn't want the lining peeking out anywhere, so it is just a standard circle skirt with the waist in the middle and it was cut just a little shorter than the front length. For this dress, I took a 40" square of lining fabric, folded it to make a 20" square, and cut a 20" arc with a 3 7/8" waist arc. I ran the bottom edge of the lining through my serger, but you can do a narrow hem, zig-zag, or whatever you want. I hate hemming curves.
Now, to make it possible for this dress to fit over the hips it will need some slits at the waist. Just make a little slit about 3" down at the very center of the back on the main skirt and lining.
Next, pin the top to the skirt. If all of the math is right, it should match up with one of the placket sides folded inward. I made some alterations at this point to make her fit a little better I took in the seams at the sides and the back centers just a little bit, leaving the top alone and tapering in towards the bottom. It made the fit a little better on her back by angling it inwards without needing to add darts. The week of sewing was such a blur at this point, but somehow it all worked out and my waists were the same size.