How can you hide depression?

I'm in middle school and I have depression and bipolar. I keep it a secret, but I have major depression and it's involuntary. I droop and sigh and rest my head on a table without even thinking. My eyes lost their sparkle and I'm dull. I used to be great in athletics and now I'm the last one. I don't do homework. I just sleep and cry and listen to effing depressing songs. I'm getting sick of the emo sh*t because steriotypes are the stupidest things in the world. but, back on topic, if you just get near me you can tell I'm dark and introverted and sad. Don't tell me to be more outgoing, but how can I hide depression or train myself to. PS: i'm 12 and take antidepressants. also, how can I stop people from calling me emo and goth and all the ridiculous bull.?