It was hyperbole, I will ammend that in my original comment.

Perhaps with late diagnoses, you not only need to combat the underlying causes that ADHD medication helps with, but also thought patterns and defensive coping mechanisms that are challenging to get rid of, as they are a result of undiagnosed ADHD

Regardless this is absolutely true. I had the luxury of being diagnosed very young and being medicated when I became a teen but I still have problems with my ADHD all the time, even when medicated. It doesn't remove the executive dysfuntion entirely, it doesn't make you function like a neurotypical, but it does help. I often take my meds and still get fucking nothing done and still sit around thinking about everything I should be doing. It is certainly far less common when I take my meds and far easier to overcome though.

This advice is unsolicited and may not apply to you specifically but I am throwing it out there incase someone it does apply to happens to see it. I have personally found that managing my ADHD symptoms has revolved around a balancing act of sleep, diet, and meds. I have tried focalin, adderall, concerta, and vyvanse in a range of dosages. Some worked really well at helping me function but fucked my diet or sleep, some didn't help at all until the doses were high enough to be physically uncomfortable, and there has not been a single one where I had a healthy diet, sleep schedule, and work routine. While this is possible while medicated I was unable to accomplish it and these forms of self care live forever in flux dependent on my meds.

So I say this with plenty of experience and passion. YOUR SLEEP AND DIET ARE MORE IMPORTANT! Obviously focusing entirely on these aspects of self care is not possible for everyone as work is an integral part of our lives but take care of them within your means even if it requires not taking your meds some days or forcing food down a throat that is repulsed by it. Sleep meds even, if necessary.

I fully recommend trying out higher doses if your meds are not helping you enough. ADHD interferes with personal life as much as it does work life so upping your meds could drastically improve your quality of life if you are on too low of a dose rn. Just pay close attention to your sleep and eating patterns. Making good grades or getting that promotion isn't usually worth the sleepless nights in my experience.

Best of luck friend o7