Can someone tell me if I'm depress?

hello, I'm 15 years old and I think I might be depressed. most of the time I'm sad and isolate myself from everyone. I haven't seen any of my friends since my last day in middle school nor have I even bother to contact them. I get mad at anyone who talks to me. I want to tell my parents but I don't think I can. I think my depression maybe link to my believes. when I was 13, I decided to be somewhat of an atheist. When I told my mom that I became an atheist, she became very mad at me saying that god and Jesus are real. Though I kept telling myself that I was an atheist, I soon began thinking more and more about heaven and hell. I soon had dreams that I ended up in hell. I told my brother about my dream and he said I wasn't going to hell, but I wasn't convince because of sins I committed from masturbating and looking at porn. I got hook on it when I was young and I saw a picture of a naked girl on the web by accident. I prayed to god for forgiveness and I hope he has, but I feel that he didn't even bother listening to me since I broke my promise to myself to stop. I tried to stop but I kept getting urges and just couldn't stop myself. Now with this whole commotion about the end of the world on the 21st (though it didn't happen), I never felt so sad and scared. I feel like ending my life. Whats the point on living if we truly don't know were we going or why were here. There's so many beliefs in the world my head is spinning. Are any of them correct. Is the afterlife better or worst then what any person has ever imagine. Or do we just rot in the ground. How can I believed in a supernatural being like god if the world operates on scientific reasons. I'm sorry if the long back story doesn't relate to my depression but it's the only thing I can think of that links to my depression.