I think you have pretty much answered your question yourself. Writing and music. These are not easy 'careers' but you can get there if you try hard enough. Is it classic music that you like? Or..? Have you ever thought about doing this professionally?
Writing is my passion as well, and my personality is quite similar - I dislike interacting with humans and can't see myself doing this for my whole life. I do not get along with them well, I find them boring, but I'm good at pretending, just to fit in. Nevertheless, getting your work published is never easy. For now I have decided to simply just 'deal with it' and have a job I dislike, while continuing my studies so I can earn money/save up whilst sill continuing my passion. I do this so I will be able to improve and then succeed at what i really want to do, and then leave my profession.
What is your degree, if you don't mind me asking? It might give us some extra ideas about what could you do.