I’ve debated how to answer this since it came in. I’ve written and deleted two long responses and four short ones.
In the end, all I can say is that I don’t have any practical advice because I do not have any experience with this situation beyond limited education and hearing bits and pieces of other experiences that are similar.
The only person who gets to determine the “positive” aspects of a disability is the person with the disability. It is dismissive for a parent to suggest that you are not “disabled enough” when clearly you have difficulties. Autism is a disability, it is disabling, and if it is not then it is by definition not Autism*. It is unreasonable and unethical to deny a diagnosis to a person because they are “only a little disabled.” They are still disabled.
Your mother is denying you a diagnosis because you aren’t disabled enough, using reasoning that is questionable at best, and the fact that you felt the need to mention she has a PhD suggests that she uses the authority of her degree and/or license to make that point. “I’m a psychologist, I know the truth.”
Furthermore, there is a very specific reason that medical practitioners of any kind should not be making final determinations for loved ones with regards to disability. A person will always have a very hard time being truly objective about family, particularly those they raised or took care of. For a perfect example of why this is, see the above two paragraphs.
The reason I have no advice is because experience tells me that you are probably up the proverbial creek without a paddle (especially if you are a minor!). Experience tells me that a medical person with a PhD that has Opinions about family can only be swayed by one argument: a diagnosis by a colleague that specializes in that diagnosis.
Obviously, you have a much better idea of whether or not this is the type of person your mother is. Maybe pointing out all of this to her will make her say, “You know what, you’re right, I’m not an autism expert. I think you’re wrong, but that isn’t for me to decide.” Maybe she will say, “I’m your mother, I know best, I don’t want to hear your excuses.” Experience tells me it is much more likely to be the latter if you are a minor, and still likely if you are an adult.
In the end, I can’t tell you what to do. I don’t even have practical suggestions. But maybe, hopefully, knowing the sort of problems involved well help you find the people who have been through this sort of thing and will have practical solutions. Whatever those solutions are, they will be very different depending on whether you are a minor, dependent adult, or independent adult.
In the meantime, please seek support and understanding from the autistic community. Even if your mother is “right” in that your issues are not autism related (maybe your executive dysfunction comes from depression or ADHD, I don’t know!), if our support helps you while you figure it all out then you are absolutely welcome here.
[*insert side rant about “what do you call an undiagnosed autistic who copes well enough with autism they seem allistic? Autistic.]