Am i being haunted by a demon?

Well i think i am being haunted by this demon, it has been following me mostly my whole life. Now my name has 3 meanings, one of which means "devil spawn" and i am mentally insane and i have manic depression, but i do not think this is just in my head. It is worst when i am at my dad's house visiting. One night it called my name right before i fell asleep and then at some time in the night it screamed at me to wake up. I thought it was just a nightmare and tried to sleep but when i went to lay down i saw a shadow and then i threw me down onto the bed. I was hysterical and frantically called my friend in a rush of tears. The next day my sister was asking me all about it. And my friend, who is also mental...but she agreed that it wasn't just me. I was afraid to go to sleep and i also suffer from monophobia, the fear of being alone. I can't even take being near the stairs because once when i was little i heard steps behind me. Thinking it was my brother, i thought nothing of it. Then i felt something give me a shove down the steps. I took the tumble and when i looked up, there was nobody there. i was about 6 when this happened. I am only 13 now but since then i have developed a state of psychosis, monophobia, and manic depression. I am also still paranoid and was then as well. As my parents are divorced, i travel a lot to my mom's and my dad's. I think it follows me because at my mother's house, I was playing on my DSI and i saw a shadow on the door creep closer, but when i looked, it receded. I keep having night terrors about that one night when it attacked me. I have gotten to a state of praying for protection at night, but when i do things like this, asking people for help, it worsens. I put a bible by my bed but when i was in our library room i touched it an i heard a voice rasp "NO" then the railing on the stairs rattled. I dropped the bible and ran away. that night i had my brother put it on my night stand for me. It did nothing, in fact the phenomenon got worse. I feel like when i ask for help from the forums, it feels provoked. when i do this, it scratches the walls. when i pray at night it bangs the walls and scratches them. One night i was sleeping, wearing a low tank top, as it was summer. I awoke the next morning to find scratches on my arms, neck, shoulders, ankle, and on the tops of my breasts running to my throat. I have horrible thoughts that it could, and may kill me. I am scared so much, but nobody takes me seriously, as i am insane, but they don't take me seriously when i say its a demon, in fact, my brother taunts me saying "was it the ghosts?!" I really want and NEED help but nobody listens to a paranoid 13 year old girl. please somebody tell me what to do!!