Also keep in mind that what you are good at doing and what you enjoy doing and what you actually do aren't necessarily the same.
I am in a very similar situation with you. I am also about to enter college, with only a vague impression of what I am going to do. Unlike you, I've passed up a chance to attend a very famous university in order to go to a no-name school in order to pursue my passion for music, a decision that I have already begun to regret.
I guess there really isn't anything to do except keep spiritually healthy and float by like everyone else.
Im curious do you regret your decision because you are finding you do not enjoy studying music or you regret your choice of schools? I played trombone and cello in junior high and have played guitar for 20 years or so, but I hated studying music. I still cant read music I play by ear.
Although I can't answer your question exactly, since I haven't actually started college yet, it is a combination of both.
For one thing, I have no chance at a future in music. I play the piano and the organ. These days, if you want to have a chance in piano, you need to be in a conservatory or under a conservatory teacher before you are out of high school. You also need a lot of connections. The standards for levels of technical mastery is so high nowadays that there is no room for mediocrity or even an only averagely impressing command of the instrument. I have 4 Chopin etudes on my working repertoire, 4 more in the process of being learned, and a Liszt concert etude (the easier one, "Un Sospiro") about half way learned, and I firmly believe that I have absolutely no chance at ever becoming a professional pianist. There are teenagers playing Liszt Hungarian rhapsodies after taking lessons for several years less than I have (I've played about 10 years). My repertoire list looks like a Hanon or Czerny exercise to them - they could play that stuff just to warm up in the morning.
My piano teacher, who recently received his music major, looked almost pained when he said that he regretted working towards a music major and now having to go back to school to get a nursing degree. He gave me some wise advice that is good for other young people thinking about music or other art degrees: What makes you a musician is that you practice every day, not that you have a degree in music. What makes you a doctor or (fill in the blank) is that you have a college degree. So music is not really a skill set - you need some other sort of skill to get by in society. - Now this, was advice coming from my teacher, who was pretty much a child prodigy - playing Chopin etudes from age eight and who studied under an accomplished concert pianist that has performed the Rachmaninoff Third piano concerto internationally on at least seven occasions. Granted, my teacher is not a Catholic and therefore probably differs in his worldview from my perspective as a traditional Roman Catholic.
So on that front, if I have no chance at a career in music, what is the point of a degree in music? Isn't it just a bit of self-indulgence that, oh by the way, comes with a hefty price for my parents to pay for me to nourish a futile dream for 4 more years?
And if a music degree is pointless, then why on earth did I choose to go to an relatively obscure institution over a very famous one just so that I could study music? (The university that I chose to go to does have a better music department in my area, which is organ, not piano, but still - why?)