But blaming either yourself or autism gets you nowhere. The only reason you should be looking at the cause of a problem is to get the information that leads you to the solution. Otherwise, asking "why" is wasted time.
The idea that 'autism is bad' can really ruin your life. It means you start to think, "I'm trapped; I can't help this; I don't know how to do this," and the only way out is the cultural idea, "Overcome your disability". There's no middle road left--either you "overcome" or it's a tragedy. But happiness and autism aren't mutually exclusive--in fact, I am quite certain that, were you to do a survey on the subject, it would turn out that we are happy at the same rate as NTs.
When you have a problem, don't blame it on autism and assume you have to solve your autism or the problem will never go away. Look at the problem on its own terms, from all angles. Get creative. Get help, if you need it. You might even learn that some autistic trait or other is actually the solution to the problem.
You don't need to be neurotypical to be happy. You don't have to be "high-functioning", nor have some special skill that you only have because you're autistic. Autism doesn't even have to give you any advantage at all. You don't have to justify your existence to the world: "Yeah, I'm autistic, but look at what I can do!" No. Much as certain autism "charities" would like you to think so, the value of your life is not based on whether you'll ever have a highly-paid job, a girlfriend, or the ability to speak. Nor is it based on how little you "cost" society. Forget all that. Forget what you're "supposed" to be and focus on who you are.