Don't worry, it's normal for autistic children to become depressed.
You say exactly this: "I fucking hate myself lately. For some reason, the other day, I got really fucking depressed and still am, I'm not eating right and sleeping a lot. It's fucking annoying, and along with that I get this constant weird feeling in my head, which I can describe I guess as a cloud in my head. But a pissed off one thats trying to rip its dick off. Because of this, I also feel like i'm perpetually about to cry, which is a fucking annoying feeling. I don't want to, and I seemingly can't. So what the fuck? My mother doesn't seem to notice the sad part though, she just thinks I'm sick and is probably going to make me get a blood test. And I fucking despise blood tests. "It won't be painful" BECAUSE A FUCKING SHARP ASS STICK OF METAL IN MY ARM SUCKING OUT THE BLOOD ISN'T PAINFUL AT ALL.

See, I WANT to talk to my mother about it, but I don't know how I'd fucking start that kind of conversation, because I'm fucking retarded. So here I sit, feeling like shit and I can't fucking do anything because I'm a fucking idiot. Thanks, brain, you worthless fucking shit."

You've already said to us what you need to say to someone who can actually help you. Depression is a serious issue, and if it takes writing down that paragraph and reading it like a script to your mother or a psychiatrist, that is what you need to do.