I am currently to a point where when I am in familiar settings like home or the pasture or if needing to do basic social functions like asking a question or going through a check out line, I think there is no way that I could be autistic
Basic social functions? I can do them, do them all the time. Even am cognizant enough to accept the notion of doing them for "practice" in the Neurotypical world we live in. Having been in this community long enough, I also understand that extroverted autistic persons really do exist, though in much few numbers than those of us who are more introverted like myself.
Yet I accept my autism for what it is, particularly being mindful that it reflects a spectrum of traits and behaviors, with some being very mild and others being quite pronounced. As for other traits that may reflect PTSD, that was something my physician explained to me in conjunction with my OCD long ago. Even then it was a relatively new term for the DSM-III.
For what it's worth, to me your sense of "black and white rigidity" across a does in fact reflect autistic behavior I can pick up on. A trait that I personally have been able to mitigate at times in understanding that so many "shades of grey" can be present in so many situations and conditions, alleviating that sense of "black and white" reasoning.
My point being that autism as something on a spectrum can reflect a variety of traits and behaviors, as well as in varying degrees of "amplitude". That such a diagnosis is likely the result of wholistic analysis. The sum total of all of your traits and behaviors as opposed to just considering parts.
Though it's all a moot point without a proper diagnosis in the eyes of the authorities, legally and medically speaking. In the eyes of the society you exist in, there's nothing as a matter of formal record to aid you in certain issues you may need help with to become financially independent. Which under your particular circumstances I would think would be a priority for you, rather than merely attempting to rationalize whether or not you are on the spectrum of autism.
Simply put, whatever you are medically speaking, it doesn't appear to be anything you can talk your way through or rationalize entirely on your own. When a proper diagnosis would be far more useful in the most practical sense. To either aid you in making real progress with your strengths, or falling back on third-party support given your weaknesses in an absence of financial independence.
Not pleasant realities to hear, I know. However it seems IMO that you are simply going in circles trying to self-diagnose when your issues are far too complex for that. Keeping in mind that members like myself, simply put it's too late for me. However I had sufficient ability all on my own to perpetuate independent living as an adult, enough to make it to a formal retirement. In essence you don't want to compare your situation to mine or others. And that in essence, your particular situation is more dire than most others.
Instead of putting all your efforts into self-diagnosis, IMO you need to harness your intellect towards obtaining a formal medical diagnosis to put you on track to either financial independence or formal support. To
move ahead with two major possibilities, rather than stew over who you think you are neurologically speaking that cannot be validated without a professional assessment over whatever conclusions you attempt to draw upon.
To be able to plot a real course to move forward in life once and for all, in your own best interest.