why am i sad

Dysthymia.

maybe you feel like your life is getting dull, now that everything is going right. maybe you actually feel lonely. it's okay to feel sad sometimes, just don't let it happen all the time. i would recommend you to distract yourself with a book or a movie or go out with some friends.

It can be frustrating when there seems to be no reason for sadness, it's usually just hormones!

Take a look at your life. Society says that you have a perfect life, but is it what you want? Maybe you should strive for the things you want(such as taking art classes) and not what the rest of the world thinks that you need to be happy.Sorry for the general answer, if you give more information maybe we could help you better.

It hurts how much I can relate to this. The scientific answer is "hormones." While that is true, I think you should also think about what about your life is making you unhappy, and above all, please seek help. This could lead to depression, which drives people to death in extreme cases. There is NO shame in needing help, and NO shame in needing to be medicated. Sometimes these things resolve on their own, and sometimes various types of therapy helps.