I do believe I had it in middle school my 7th grade year but the really stupid thing was, I genuinely thought depression came with puberty/growing up. I literally thought everyone, whether servere or mild, went throu some sort of depressive episode with low self esteem and challenging thoughts about themselves. Since I thought it was just a phase, I didn't talk about it at all, I hid it, I thought I would just roll throu it and make it out like nearly everyone else seems to have.
Spoiler alert: I didn't 'tough it out' like I thought I would. I pushed away friends I had, my grades fell badly, I was unable to focus in classes, I lost interest in all my hobbies that used to bring me joy, I dragged thou my days, didn't talk to anyone, I ate less because I had low self esteem. The only reason I got out of bed was because I had no choice, my parents would never have let me stay home just cause I didn't want to go to school. One time I briefly -I think it was only a few seconds- blacked out because I had skipped lunch that day. At first I didn't know why I had blacked out, I just remembered being very light headed, my vision goin in and out, losing hearing, struggling to swallow and feeling like I wanted to throw up. After a while it hit me that 'hey stupid, you didn't eat lunch, you don't eat food you feel bad'. It was this and when all my teachers had to have a conference with my parents about me failing all my classes that it finally hit me, 'hey maybe not everyone goes throu this, grades fall so bad that all 8 teachers need to have a conference with my parents, maybe not everyone blackouts due to not eating just one meal (I was also prob over heating at the same time) maybe not everyone goes throu depression when they're still going throu puberty'.
So I started to talk to a teacher I trusted about it. I told her how I felt and she really helped. I talked to another person about it, she was in the peer counseling classes at the school. I decided to eat because I hated the sensation of feeling light headed and what I felt before blacking out. I wasn't eating because I felt fat, but only skipping one meal didn't change my weight (I only skipped lunch at school because my parents weren't there to see me. I also ate less at dinner but didn't throw up cause they would see me and I tried to hide everything as much as I could). Everythin turned around and life got alot better. I made new friends who I was still friends with in the 8th grade year and one of them my freshman year of high school. I wasn't so hard on myself, and I started to enjoy things again.
Sometimes I worry that because I never went to a professional about it that it's not really cured, but I only feel this way when I'm extremely upset with myself. I'm still a little hard on myself, which is what I fear starts to trigger it again, but overall I'm much better then I was then.