I came here to see the post, and found this amazing advice with it. To have it put that way did resignify some of what I already thought I knew 🙂
As @Tónskáld already talked about harmony and form, I think I'll say my thoughts about the orchestration. It think this is executed too much as a bureaucratic task, as if you had to simply assign the lines you wrote to whatever instrument you have available, and not enough as a craft in itself. The way everything is doubled indicates that you didn't use each instrument because of it's specific timbristic character or because you think they will bring out the character of your ideas even better, but that you wrote a line, stuck it onto a group of instruments and moved forward.
Having an orchestra this size, orchestration becomes a matter of its own, and it can single handedly make an average piece amazing, or the oposite. For that reason, I would recommend writing for smaller groups. You would have much more control of what is going on, while having more contact with specific instruments, so that further down the line you can use them effectively.
As to being a composition major in college, I can perhaps help you with something. I'm going to the Royal Northern College of Music later this year for an undergraduate degree in comp, so whatever doubt you have about applying feel free to message me. That being said, the process in the US might be quite different when compared to the UK, but I'm sure they have their similarities too.