Depression in teens? I think I am.?

Okay so im always sad. I mean i can be happy, but its not a lot the only time im rely happy is when im home alone and my music is rely loud. I also was happy at our dance (school dance). But all other times im sad, im sad at school, home, bus, car, dosent rely matter. My friend the other day asked why im always so sad, i mean i kinda know why im sad sometimes, but i know that's not why im always sad. I don't like to be sad all the time i want to be happy i just can't. Does it sound like im depressed? I don't want to talk to my parents about it or my school consular.I have a older sister i could talk to about it, but im scared to do that or get help. My friend says they might give me pills to make me not sad if i go to a therapist or something. But i don't want them because he told me and iv heard it just takes all your feelings and emotions away. Plz help