I am composing a nocturne in Bb. To me Eb and Bb fit very well as keys into the definition of a nocturne(music that evokes a nighttime feeling).

Here is what I plan to do in the nocturne:

Section More Detail Proposed length
A Establishes Tonic of Bb 7 measures
B Modulates from and back to Bb 6 measures
A' Octave variation 7 measures
A'' Tremolo of a 3rd added 11 measures
B' Octave variation 6 measures
A''' Right hand down an octave, modulates to parallel minor at the end 12 measures
C Contrasting key 5 measures
D Modulates from minor to parallel major 12 measures
A'''' Faster triplets 7 measures
B'' Faster triplets, Left hand down an octave 6 measures
A''''' Faster triplets, both hands down an octave, right hand plays melody in octaves like in A' 7 measures
C' Octave variation, slower triplets 10 measures
D' Octave variation, slower triplets 12 measures
A'''''' Slower triplets 14 measures
Ritardando Brings piece towards an end At least 3 measures
Root position chord in unison Perpetuates the piece 1 measure at the most
1st inversion up an octave in unison Perpetuates 1 measure at the most
2nd inversion down 2 octaves in unison Final ending chord 1 measure at the most

Now I do have mini ritardandos(slows down by 10 bpm) for each B section towards the ending measure of that section and probably will for each D section as well but the ritardando section would get even slower.

Here are the PDF and mp3 files of what I have composed so far. I am not even halfway there yet:

Nocturne in Bb.pdf
Nocturne in Bb.mp3

What do you think of it so far? Should I add a B section between the third and fourth A sections?