Yeah, I definitely agree that it is a symptom, not a disorder. At the time I was anxious and depressed following a bad drug experience which sort of made me take a look at my life and made me question who I was and the world around me. I guess it opened up my eyes to a lot of things about myself that I really wasn't able to handle. My depersonalization would often follow with panic attacks and I was 16 at the time too. I dealt with it on my own, only telling a few of my close friends. I began running everyday, really focusing on the people around me who I cared about and spent a lot of time reflecting and accepting myself. I still get anxiety sometimes but nothing to that extent. it was a pretty terrifying experience, especially if you don't know what's going on, you feel like you're going crazy. I find what helped me was to always be busy, because I was really stuck inside my own head just dwelling on negative things.