Hi NS,
Congrats, you are doing a very nice job with this piece. You have it in better shape than I do at the moment, but this is a piece I have played for many years (since I was about your age, 20 years ago) and would be glad to share with you a couple of concepts you may choose to explore. Naturally, judge for yourself.
First of all, this piece is based on a Watteau painting about (minors, cover your eyes) a couple that goes to Cythere, an island where pleasure is the name of the day. The score reflects this sensual atmosphere very well, and thinking of it will likely deepen your understanding of the structure and the general layout of the various climaxes in the piece. Variety of color is called for, just like in Pictures at an Exhibition (a work i think would suit you well).
On a more technical level, you may want to experiment with a greater variety of speeds of attach and of finger angle and mass engagement. This is how it works: you can play just as loudly by playing the keys with fast velocity of attack and not much weight (mass, really) or by pressing the keys much more slowly but engaging the larger muscles in your apparatus (mostly the back muscles, particularly the shoulders). Same thing with finger angle, the smaller the surface you are using to play, the more piercing and less fat the sound you will produce. Flat fingers = fatter sound. This will improve you color palette, your ear will let you know. Note that this does not affect rhythm or tempo, as simply the action of playing occurs earlier or overlaps with other gestures.
Feel free to use the una corda pedal. I think I did not perceive any use of it and it makes a lot of sense in lots of places. You should experiment, although if you want them, I will be glad to tell you the ones I use some times.
Post more.
P.S. Nice Rittmuller.