Please help...

I haven't had it diagnosed yet, but I'm pretty sure I have depression and anxiety. I have panic attacks all the time and I cut myself. I am so unhappy, I attempted to commit suicide last year and I want to try again. The only thing that is stopping me from doing it is my mother. I need to talk to someone but all the "online help" I get just says that "'my problems are too serious for me to talk to someone" and I don't want to talk to my mom about that or a theripist because I can't even explain what's going on inside my head. I cut my wrists last year but I stopped because my mom found out. Then I relapsed in May free 6 months without a cut and I've been cutting ever since. The cuts are on my upper thigh so nobody can see them. But I need help as I don't want to asks for it. My family is broken. My dad wants nothing to do with me. And my grandparents expect me to be "all that." They want me to be the smartest in my class. But I can't be (I take school in French when English is my first language so us double hard) and today I found out I have the worst marks in my class. I'm the most stupid person ever. I'm also very overweight. I'm 13, 5"7 and weight 300 pounds. I feel like everyone thinks I'm mean and annoying and I know I can come off a little different ad "meaning" sometimes but that's just my way to e funny. Funny is my thing. That's how I escape everything. And even my friends say I'm mean sometimes as a joke and it really gets to me. I just wish I never existed. What do I do? Who do I talk to? What websites can I ask for help?