@coffee77 Welcome to Mayo Clinic Connect. I can see from your profile that you are new to the Caregivers Support group but not to Mayo.
https://time.com/3755176/doctors-diagnose-alzheimers-dont-tell/# This is an excellent article about why doctors won’t diagnose.
Here is an article from the Alzheimer’s Assoc. On benefits of diagnosis.
https://alzheimer.ca/en/about-dementia/do-i-have-dementia/how-get-tested-dementia-tips-individuals-families-friends/10#:~:text=People%20with%20dementia%20can%20live,plan%20for%20their%20future%20together.
One article suggest that you find a geriatrician (a doctor who specializes in treating the elderly) and you might have more luck.
Would a diagnosis make a difference in how you care for your mother?