You're never quite finished when you think you are, ね? I was listening to the chorale and finishing the dynamics, when I started to really think about what Brian meant when he said that the piece needed to be longer. I timed the first half of the piece and compared it to the second half; it seemed balanced. I listened closely to the "my heart will rejoice" section; I played around with some changes which I will most likely abandon. Then I got to the next line, "I will sing to the Lord". This was it. This was the section that needed to be longer. It's a different theme melodically, and a little different in style; the problem is, it's only 4 bars long, and then you leave it behind and move on to the next section. It's a nice idea, but I don't develop it. It's faster in tempo than the rest of the piece, and you just need to spend a little more time there, to give you a chance to enjoy and appreciate it.
It's a little daunting sometimes to tear something apart to rework it, but I went ahead and made a copy of the file, and began developing this theme. I'm rather pleased with where it's going. Might take me another day or two to refine and polish it, and finally wrap things up.