you need to explore EQ more. Take a eq on only one instrument and make a SHELF. Use that while looking at the display on the limiter on the master. Make sure you have a flat volume hitting the grid and you have a at least a "volumely good mix". (in terms of audiophile).
You have good resolution in your sound, but you need to work more on your dynamics or leave the master without a limiter.
The composition I would say is an midi-file? ... Idk, If you made this score you're self I would be deeply impressed just by that.