Diagnose my feelings?!?

If it's been going on as long as you say it has that's definitely a moderate to serious depression. Have some experience with the problem myself I've had it for about eight months now and I can tell you its absolutely no fun at all and trust me it will likely get worse before it gets better. If you can ask your parents for help. They will likely say the typical 'oh it's all part of growing up' nonsense at first and you might have to work to make them see it's NOT! People are not supposed to feel this way at any age and at this point I think you may need to get help. If you can get your parents to understand how bad things are really getting you'll have an easier tiome getting help, which trust me might seem hard but has to be done.