This is totally cool. There is no one around here with whom I can have this kind of "conversation." However, it's Saturday (errand day), and I can't take the two or three hours that I would require to give this the reply that it merits.
Still, I can't resist one observation: The difference between inner and outer reality. Science looks at the outer reality, that which is quantifiable, as the final word. If nothing else, duplicability requires it.
But inner reality must be satisfied before outer reality is. That is, if I observe something and decide that it represents my reality of the moment, the "test" that I have applied is not quantifiable because it is not repeatable by another individual. My decision that it meets my standards of reality are completely personal. It really comes down to perspective. The individual who contends that outer reality is the "true" reality sups more from the scientific plate; the claim that inner reality is the "true" reality belongs more to the realm of the philosopher.
Okay, one more thing. There are pathologies in which an individual is convinced that he or she doesn't exist. The most extreme one that I have found is called variously Cotard delusion and Cotard's syndrome. It is contradictory to say--and believe--"I do not exist," yet, it happens; your statement that it is logically impossible to doubt one's own existence makes perfect (logical) sense, but humans don't always make sense.
When I now say "find the flaws," I am not being snide. I have a great deal to learn and every time I read something that you write, I have to spend hours figuring out what you mean and how I can counter it. It isn't just that it's "totally cool" but that it's totally educational as well.
Qualitative, personal, experiential, imaginary, internal perception is the source of all meaningfulness.
Quantitative, verifiable, scientific, true, extant, factual reality is necessarily emotionally meaningless.
Intuitively we often conflate what is "real" with what is "meaningful" when actually they are mutually exclusive.
What is real cannot be meaningful (in and of itself) and what is meaningful cannot be real.
Standards of true and false only apply to our "shared external scientific" space where we need to negotiate standards of true and false.
Internal Qualitative experience is not "less true" than shared Quantitative reality. It is simply not held to the same standard (it has no truth value). It is unfalsifiable.
In the same way that "red" is not properly described as "less blue".
It's something else completely.
People can doubt their existence, but it doesn't make them disappear. This makes their belief provably false.
It is however, perfectly valid to doubt one's own meaningfulness.