Do I have depression, schizophrenia, etc.... I don't know which.?

Let me start by saying I've always thought I had depression. I know I have something at least related to depression, because I've contemplated suicide many times before and it's never during a period of grief. The reason why I don't know anymore is because I've been taking anti depressants for many years now and I've never noticed a real change (my mom says it's a little better). I see a shrink to get my pills and he thinks it's possible I have schizo, but I'm not sure and I sure as hell am not going to take a test to find out I don't have it if it's 4 days, when I already work and have school all of the time. I never hear voices or see things. When I do something wrong (trip, move in my chair too much (I have a bad back, so positions are hard to stay in)) and I hear people in the back of a room start talking or laughing I think it's about a joke, but I kind of believe it might be them talking about me. I really don't want to be hated for saying this, but it's honest and I can't help this thought of sometimes feeling like a lot of people are dumb and there are only few people who think a certain way, as I do. I know it's something depression related also, because I'm just sad or mad all of the time and rarely happy. It just makes me want to cry, because I feel like my life is just hopeless now and not going anywhere. I'm pretty internal and am not the person to walk up to somebody and start talking to them. I always feel lonely and stressed. I get so tense all of the time and I notice it, because my muscles get tight when it happens. I always have a flat indifferent expression, except for when I'm around people, trying to be normal. I'm not limiting the possibilities to depression or schizophrenia. I know it's not bi polar, because I don't have any mania in my life. I'm pretty well educated in my mind. I am 18 years old going to a technical college. You guys. Please, I am not joking, and I really need help. I just want to know what I have so I can get some medication that will make me happy. I've tried therapy, but it didn't do anything for me. I've tried so many depression medications it's not funny and I've tried most everything suggested to me to be honest. I get enough sleep. That's the one thing I think isn't normal. I don't have a hard time falling asleep. I do have bad eating habits though and every other symptom of depression. I kind of just want to withdraw from civilization and become a hermit living in the woods, because I'm just so sad. Most of my friends never thought I had any emotion really, because I am always indifferent physically, but inside it's so sad. Can anybody here help me a little to pinpoint what I have or get a general idea of what is wrong with me. Every day I look out the window and see the same thing. It's like a movie with only a couple camera positions (the windows in the house being the vantage points). Oh yeah and everything for me is dull and seems bleak and lifeless. I try to entertain myself by skateboarding, playing baseball, watching television and playing video games to get away from life and forget about how horrible it is, but really when I'm done doing those things it's back to ...my life. Also, the things I do to entertain myself don't seem at all what they used to feel like. They have no flavor. It's like the midas touch. I can give more information if it deems necessary, but please believe me. There is no reason for me to make all of this up.