A very thoughtful piece, I really like it :) Good luck with the contest!
I honestly haven't got much bad to say about the piece as it is pretty wonderful! The only things I've noticed that you could do differently, and this is only from personal opinion, are:
- Have the background instruments play a bigger role during the build up to around the 2 minute 20 mark. So after the main melody is introduced, have the instrument fall off to the background for a bit, making it quieter and bringing in the other instruments for a while and then reintroduce it later, combined with all the other instruments, to give it a greater effect.
- You could introduce another fun instruments before the 2 minute 20 mark to add some variety, perhaps something like a harpsichord or something more fitting and have it play some melodies while the main instrument takes a seat in the background.