First of all, kudos for not over-using the string section (at least in the first movement). Too many people see the orchestra as:
Strings
Melody watBrass
lolololololololol so epicWoodwinds
wtf I ain't using thesePercussion
There should be an abundance of large things, and they should be hit very hard.Right, now I can get nit-picky.
Everything that has been said in these two movements (all of the musical ideas, phrases, melodies, etc.) could have been established, exposed and concluded in little more than three minutes. At most. Nine (going on ten) minutes is way too long and it shows.
The piece is so long and stretched out I was bored. It felt like you were aiming for quantity rather than quality. You worked methodically and systemically through the work by establishing a harmonic base and adding ideas onto the top every sixteen measures or so. I could predict exactly when a new instrument would come in and add to the piece. I shouldn't be able to do that. The music should move in unpredictable ways and lure the ear into a false sense of security before blowing it out of the water with an unprecedented cadance. Don't ever let ideas or dreams of length get in the way of succinct, tight composition.
In order to achieve such length, you will need to look at variation. Listen to the famous
Symphony Nr. 5 - Allegro con Brio "Fate"; Beethoven (Reference Score Here)Look at how Beethoven takes the main idea of the work (Profoundly stated in the first four bars) and keeps them exciting all the way to the climax of the piece (Note that you should ignore everything else here except his variation; Beethoven was a genius among all fields of music but our focus is specifically his variation). I'm not asking you to be as fantastic as this man, but just look at ways (beyond layering of sound) to vary your melodies and ideas.
After all of that though,
I don't want to discourage you from making music. Music is fantastic and I'm so happy you're having a go. Keep at it, the only way to improve is practice (and a little help from others). Keep at it, man.