Depression

Hi. I am a 17 year old High school student. I live with my mom and step dad. I have average grades and a few friends. I have a problem. Though I have read up on most cases of ADHD and all of them say that depression is related to the disorder i feel it getting worse with each day. I am in therapy once a week since i go to work and go to school. It doesn't really help anything. I always feel alone and isolated even when I am around people. I have very low self esteem and have no hope in my life. I am also dealing with an over weight issue. I am trying everything i can to fix these problems but I feel no matter what i do or how hard i try it's not making a difference. I have talked with my parents and my therapist about it but they don't know how to help. Please help. I don't know what else to do and I don't have a lot of money.