Hello @chocolatepeach I recently got back onto College Confidential and noticed your post. You are very articulate about how you are feeling and that is wonderful. It is now the spring semester and I wonder how you are doing/feeling. Regarding your back pain, I don’t know where you live, but can you look into finding a Performing Arts Clinic? Medical insurance generally pays for this. My daughter, violinist, was helped tremendously by clinicians (neurologist, physical therapist, occupational therapist) who specialize in treating musicians.
There are many ways to do music, and I truly hope that you, so clearly talented and dedicated to the piano, keep looking for your unique path. You will find it. Also, a slight tidbit - maybe build up your piano time, and play in smaller increments, with breaks where you stand up and stretch (every 10-15 minutes). Also, exercises to build up your core strength, very important. It will help support the muscles of your shoulders/arms.