Should I go or should I try to handle it myself?

I'm a 16 year old female who lost my father to Leukemia almost two years ago. Ever since then, I've been having noticeably different emotions. I get easily angered and cry over almost anything. I also recently lost literally all of my friends when they started to betray my trust. They also tormented me through cyberbullying and writing degrading things about me on the bathroom stalls. That seemed to make everything worse. I am also almost always alone, since my Mother has to work all hours of the day to support our family. So, with her being gone, I have no one to confide my problems to. I do see a counselor every two weeks, and I have requested to see her more, but she denies my requests. I also see a psychiatrist and am on 150 milligrams of Zoloft, which also does not seem to be working, and he too denies my request to try a different medicine or higher dosage. To make things worse, my only friend, who is also my boyfriend, is now thousands of miles away to visit his father, and does not wish to talk to me, much less listen to what I have to say. We have been dating and bestfriends for almost three years now, and I do believe my mental state has jeopardized us from becoming closer, and in fact, is most likely making me lose him. I feel helpless and hopeless, and sometimes I take my prescription pain pills from surgery to ease the pain and escape reality. I also try to over-dose on my Zoloft or Tylenol in order to maybe pass out, since I am unable to sleep at all anymore. Although I may have problems, I'm not stupid and I know what I'm doing is wrong and I do understand I need help desperately. I want to check myself into a mental hospital, but I don't want to leave my Mom behind and hurt her. She is taking the loss of my Dad pretty hard too. But I am also concerned that if I don't get help, I may end up killing myself despite my strong belief against it, and then my Mom would never see me again. Please help. What should I do?