Your composition teacher is a person you trust, so their opinion matters to you. But remember that they were talking about one single other student's experience, not many students, and not their own experience. And that student had a different diagnosis than you do. Your case is your case and your education is your education. If you want to pursue music, and you left your conservatory program on a temporary basis, keep the school aware of how your treatment is progressing, keep them aware of your intention to return after a medical leave of absence, and then go back.
You may need to take more time off than you originally intended, and that is fine. Your health is important. Finding the resources and treatments that work best for you may take a while.
There is no reason this needs to be the end of your musical journey, unless you happen to find another path that you like better. Take your time. Get well. And then decide on the path that feels right to you.
Be gentle with yourself.