Yeah, I totally get that having a disability can be frustrating simply due to the effects of the disability itself, even if people do treat you decently. I get sensory overload, periodic depressive episodes, executive dysfunction, and general autistic social cluelessness, and that's not exactly a nice experience. But everybody has annoying and even painful parts of their lives; I don't really think that having a disability means your life must be horrible. After all, able-bodied NTs get stuck in traffic, get mugged, break up with their significant others, or have their children die young. Everybody has bad things happen to them that are anywhere from annoying to devastating. For me, some of them happen to be related to my disability.
I don't want to trivialize it. Some things you experience because of a disability really are very hard to get through. It's okay to complain about those things. And it's probably true that most NTs really don't know what it's like to be in the particular autism-related situations you get into. Still, universally, we all have things in our lives that absolutely suck; so disability isn't so foreign and far removed from "normalcy" as many people think it is, because even if NTs don't have the experience of being disabled, they do have the experience of going through the harder parts of their own lives.
It's harder to deal with crap in your life when it feels like you're the only one who ever had to deal with it. You don't feel so alone when you remember that both disabled and non-disabled people have to go through frustrating and painful experiences that are unique to their own lives and situations--often with the knowledge that no one else, no matter how sympathetic, could ever quite understand. Though, on a more cheerful note, both disabled and non-disabled people also have positive, interesting, encouraging, peaceful, and exhilarating experiences that mostly make life worth our while.