Suggest Remedy For Teenager To Lose Weight

Hello there, I'm 15 years old and I weigh 260 lbs. I'm 5'7 1/2 inches tall and I'm a girl. I have very low self esteem, motivation levels and I can never seem to get ahold of my weight. I'm moving and I'm going to join a couple weight loss clinics for children and teenagers, and also join the YMCA. My mom is 290+ and my dad is 170+, my parents aren't exactly skinny and I come from a family of big people. I've been bullied alot and I want to be skinny. I have a slow metobolism, and I don't eat alot its that I'm very inactive and I can never seem to get any motivation. I want to find a way a good way to lose weight for girls around my age in my situation, also what would a good workout be for me at the YMCA? I would love to hear a good answer.