Why is my Medication ALWAYS out of stock

I am supposed to take a it every day for three months before I get a refill but Walgreens seems to always never have the medicine I need. My friends who also have ADHD seem to get theirs exactly when they are expected to but me? No I can't get mine, I order it every month exactly when I'm supposed to and every month it's out of stock and I wait for them to call me back saying they filled it only for the order to have been cancelled. I re enter it again and guess what it's out of stock. I just don't understand why this is happening

I haven't consistently taken my required medicine in 4 months. I got it refilled Once I'm those four months and it wasn't out of stock. So I have 3 months of not taking my medicine. Sorry this is mostly a rant and I apologize I just needed to get it out somewhere that people would understand.

Thank you.