Depression at a young age

My name is Chloe and I am a 15 year old teenager that is suffering with depression.

Unfortunately I don't have the guys to tell my parents that I am suffering depression. How do I know I have depression if I haven't told anyone? Well, I am always unhappy with something, the way my hair looks, my general appearance, or just life itself. I have never had suicidal thoughts, thankfully. But I have been thinking of self harming, and have done so on a couple of occasions. Nothing to and, just scratching and biting my arms and hands, then rubbing them so the marks go away quicker.

I am also scared that I am going to develop an eating disorder because I really hate eating. I don't know how to explain it other than I think of all the things I have done to make people unhappy, so I punish myself by not eating, even when I am in pain because I haven't ate, I just don't eat.

Every night is like a bad dream because I always want to cry, yet I can't because somhow I feel like I have let down my family, because they want a happy and funny little girl, but I don't always want their company because it makes me sadder to think that I am there wasting their time feeling unhappy and miserable, so. Literally live in my bedroom, only ever coming out to go to the bathroom or get a drink. Why am I always feeling lonely and miserable?