I'm so sorry you're feeling this way but when you feel like nobody cares or notices how depressed you are, I hope you can remember a lot of us on here who care and are thinking about you. You shouldn't be coping with all of these emotions alone, especially at 16.

Is there a school psychologist on campus you can talk to? When I was a sophomore in high school, I started seeing ours when my dad became ill. She was quite young and didn't offer any groundbreaking advice, but it helped having somebody neutral to talk to.