Is this considered depression?

So I first started feeling upset or sad about life when I was in 3rd grade. I know that seems young but we’re all different I guess. I go through phases where I’m happy and then I’m back to sad again. It’s like I know everything happy in my life won’t stay so my mind just snaps back to sad. I don’t know If you would call this depression or not. I’ve cut myself a few months (with a really sharp pencil) and the pain felt good but my friends and especially my boyfriend didn’t take it well so I stopped. I get urges to do it again but the thought of getting caught by my parents scares me enough to stop me from doing it. My parents have no idea about any of this and i plan to keep it that way because It’ll make things easier for me. I don’t have thoughts of suicide or anything like that. So I guess to ask a question would any of this be considered depression?