Extreme money stress....I don't know what to do?

Hi, im 21 and live at home, I suffer with severe depression and social phobias which i'm currenly "trying" to get over through therapy. Therefore I am unable to work at the moment. I live with my mum, who works in a school as a Teachers istant. My mum is really badly stressed out by money, she got paid app a week ago, and she can no longer draw money out her bank account as all her money has been taken for the mortgage and all the bills plus 1 weeks shopping. She now has to ask me to lend her money for the shopping and bus fares...thing is i'm in my overdraft already. We can't go through this every month its ridiculous. We are hoping to put our house up for sale soon and buy a cheaper one and have a much smaller mortgage, my mum is also looking at getting a new job she has an interview tomorrow. I just don't know what to do, it's really affecting my depression aswell, my mum is just so stressed and I don't know what to do. If you have any advice I would really appreciate it. Also I have a medical essment for ESA next week, which would really help having that money, but im really not banking on it from hearing that most people with mental illnesses get turned away :(