Depression

I am very sad

To the point where i think I'm depressed.If I tell any grown adult they'll think I'm being rediculous . I have been like this for over a year

What do I do???😢 UPDATE: thank you everyone...it's been another hard year now but finally my mum's getting a therapist for me because she found the blade along with the blood and depressing drawings and writing. eve didn't say that some of you replied so I'm sorry if I didn't.Also, I didn't really know how to express myself that day so I said I was just feeling sad ,but there's more to sadness than most people could imagine.Once again, thank you