Halfway through the project, I almost ripped the whole thing. It did not look large enough to me. When measured flat, the top piece had the right dimension. Yet, it looked so small. There was no way it would stretch down to below waist, I thought. My DH suggested that I finish it as it was, and if it turns out to be too small, knit another one. Well, it was the right advice and I am so glad to have listened to him. The knitted fabric turned out to be so elastic that it did reach the length I wanted.
So, here I am very pleased with the finished garment. I used only 7 balls of the yarn.