I think I have been suffering from...

I think I have been suffering from depression since at least my freshman year in high school. No one seems to know. I told my dad, but he said that I am not, that I couldn't be. Is it not possible for me to depressed? My sister has been through living hell and back and her pain and anguish and my mom's and my own problems have haunted me so terribly. Does no one see that the hurt I feel runs deep? I am the only one in my family that does not take any medication - so I have taken nothing for depression. I am now a senior in high school and I still have darkness in my heart from the pain my family experiences. It separates me from God. There is one sin that haunts me every single day of my life that no one knows about, I can't seem to stop. My struggle is trichotillomania (hair pulling) in the hidden regions of my body and it terrifies me. (I pick at myself until I sometimes bleed.) I don't go to anyone for help, because I don't want to be labelled as a freak. I want it to go away. I want to heal. All this hurt and pain that is still with me from the past and I still see in my sister every day has led me to be quite an aggressive, competitive person. People fear me sometimes when I get that way, and it makes me sad and ashamed when I can't control my temper and my aggressiveness. My sister has depression (and so does my mom - chronic depression) and she has OCD. She was once admitted to a psychiatric ward, because she tried to kill herself. I have thought of the different ways of suicide, which would be the quickest and least painful - but I would never take my life no matter how much I want this life to end. I actually wouldn't trade this life in, because I have experienced some wonderful things, because of God. He has taken me around the US doing service for him. I have been from the eastern coast to all the way to Alaska. It would be such a selfish thing to do to take my life and it would hurt those I love. There is so much pain in my family. It runs so deep. My sister runs around undisciplined and doesn't respect authority. She is in college and just takes random classes and has no planned direction for her life. I am so troubled by her decisions and her pain. I am a churchgoer, a Christian, and I believe in Jesus as Lord and Savior - or at least I think I do. I struggle with doubt a lot, because of how this pain seems to cover my heart and separates me from God. I just want to be able to fully believe in God and I just want the pain to go away and for my sister to be saved. I want all the pain of the past and present to be erased from my family. I want to cast away the pain that holds me back and fully run to God.