the only place that consistently has my medication

is there a Costco near where you live? if so, you might give their pharmacy a try (you don’t need to pay for a Costco membership if all you’re doing is getting a prescription)

I had similar challenges finding a pharmacy that consistently has my ADHD medication in stock. a few months ago I tried Costco based on a recommendation from my doctor, so far they’ve been able to fill my prescription every month no problem.