Am I worthless? Am I a failure?

I'm 18 years old with asperger's syndrome. I have never had a girlfriend in my life, I've had a really crap life in high school, and I've failed my 3D course in TAFE and I will be banned from going out for the rest of the year if I fail my course. I'm horrible with learning different things, and hate having to ask for help because it makes me feel like an idiot. The only thing I'm good at is music and my parents forbid me to become a musician because they think I won't make a living out of it. I also want to get a tattoo on my arm of Type O Negative's symbol as a tribute to my hero Peter Steele. My parents say that all people with tattoos are scum of the earth. I'm uncomfortable with the way I look (5'9, red hair, little freckles) and don't think I'm ever going to get a girl. I'm really shy as well. I blame myself for being born with this disability I have because if I didn't have this disability, I wouldn't be struggling. Everyone is having the time of their lives while I'm stuck in pain and agony with this really crap life I have. I need help. :'(