It isn’t just your fault. Thank you for taking the time to write us. Your mother’s drinking, personality, physical and emotional abuse of you are significant. Taken together it shows that the majority of the problem lies with her parenting skills — not you.
I would start by talking to a trusted teacher or counselor at your school. He or she will be in the best position for offering suggestions about what to do next. As a 15 year old your mother needs to be doing a better job. Although you didn’t explain the situation in detail — if you were supposed to be taken away from your family because of your mother’s behavior you may want to contact the people recommending this — they may also be in a position to help.