Ok I think I have it figured out. I used to try to sew my dresses in that way too but it was difficult to get it sewn straight on both the top and bottom. I know sew the dress ruffle (already gathered) to the bodice back with the ruffle and back right sides together and the ruffle bottom pointing towards the neckline. Then I stitch the right side of the bodice bottom to the whole thing leaving an opening where the ruffle is joined. Turn the whole thing rightside out and then stitch over the opening where the ruffle is (turning the edge under first of course).
Hope this helps.
