Should I Get Help?

(TRIGGER WARNING)
Hi- I'm fifteen years old and I was wondering if I should see a therapist or go to some sort of group therapy. 
I remember when I was younger like six or seven, a boy my age touched me. He stuck his hand down my pants and tried to make me touch him too...I remember crying and a teacher came over. Boy ran into the bathroom and I never told anyone besides two close friends who I became close to in high school. 
I believe my first attempt of suicide was in 5th grade. I cried to hang myself but my Dad walked in. He held me and cried and told me that he wouldn't tell my Mama. During that grade and for the rest of my years so far, I have abused drugs and got involved in underaged drinking. It isn't an everyday thing. Just every now and then. 
Middle school started and I tried my best to be happy. I had great friends until 7th grade. My friends left me and said things about me. I tried so hard to be their friend. My Mama told me it was my fault and that I didn't try hard enough. I made new friends...but I started to cut myself and I wasn't sleeping. Scars and dozens of scabs up both of my arms were noticed. The counselor called my parents. I was taken to the hospital to talk to a whole bunch of doctors. 
After that I went to a therapist due to hospital orders. I only went for two days because my Mama told me to get better so we could move...I slapped on a smile and we never went back. 
I moved to NJ. My brother attacked me in a hotel room. My parents yelled at him and took him out to eat. I stayed in the hotel room because I couldn't stop shaking and crying. Months after, my brother choked me at my uncle's house. I kicked up off of me. I didn't tell my Mama for months. I only told her because she told me that I shouldn't be ignoring my brother and that I will have him for the rest of my life. I told her about what happened, she scolded my brother, and that was it. 
Eighth grade was so long. I was still cutting. During the school year, I lost my closest loved ones: my Nana (she lived with us for years) and my first pet, Gypsy. Nana died in September 2014 and Gypsy died in March 2015. (Nana was supposed to get surgery to get better but at the last minute she decided to get a lethal injection. Gypsy had a blood clot in her leg and she died in front of me.) 
High school starts, I lost my friends due to them bullying me. It was for the better. I made new friends. Best friends even. I told them everything. They tried to make me get better. I love them so much. 
I move again to AL. I hate the school and I miss my best friends. I cut again and keep a knife in my room. I struggle to sleep. This Summer, I visited my best friends again...they are fighting and don't talk anymore. They hate each other and only like me. Before I left NJ, I managed to relapse by clawing at my forearm. It was bleeding but quickly turned to scabs. My brother and Mama saw a few days later but I told them I fell. School is going to start in less than a month and I haven't been sleeping well all Summer. I want to get help but I don't know if I actually need it AND how to ask my parents. I don't want them to think I'm doing it for attention or to be cool (I'm only saying that because in 7th grade my Mama thought I was cutting it to be popular) This may be useless information but I'm a Army Brat. I'm also Pansexual but my parents don't know. They are accepting and support LGBT+ rights but my Mama feels like everyone is coming out all of a sudden to be cool...so I only haven't came out because I don't want her to think I'm doing it to be cool. I experience headaches a lot. And that's about it...I tried to summaries as much as I can. I'm sorry for it being long. I'm also sorry if there are any types of errors. Not trying to sound whiny but please answer as soon as possible. Thank you for reading.