Have you tried Lemon Balm?
I recently got diagnosed with ADHD at 29. I've been drinking lemon balm herbal tea (tisane if you know what's up) for a while now because I enjoy the calming feelings it brings. Based on my research, this seems to be because the lemon balm plant has some kind of compound in it that reduces cortisol levels once consumed. I found it interesting because it would help me focus, and I did not understand what cortisol had to do with that.
I've been listening to a podcast called ADHD with Jenna Free, in which ADHD is framed as a condition that keeps you in "fight or flight" mode. This suddenly made things click for me on the lemon balm! My guess is the reason it's been helping me focus is because the lowering of my cortisol as I drink it allows me to have a clearer mind so I can better focus on the task at hand.
I was wanting to see if anyone else has tried it and is having a similar experience. I also just wanted to put the idea out there since it's a relatively minor thing I've started doing that's helped me tremendously!
Try at your own risk, I know these things can sometimes interact with meds so make sure to do your own research if that worries you. I take wellbutrin and haven't felt any negative effects from the lemon balm.