There is a lot going on in our heads, so sometimes I find my temper is shorter than a durian queue in Double Bay. That's to be expected. Brain fog is a symptom of MPNs as well and thet could be leading you to think your ADHD is worse where, in effect, your brain is just processing a lot of information, concern, worry, and life things all in a way that is as clear as driving up Kosciuszko in a snowstorm.
Giving yourself time to breath is hard - but essential. And it's exponentially harder if you ADHD. Making time to work on your mental health is a real challenge but, if you can do it, it helps. I find I spend a lot of time in earphones trying to block out the world and change my focus from the rubbish things to the good things.
Don't be hard on yourself for having a short temper. You're dealing with a lot and sometimes it is just sh*t. But then the sun rises the next day and some wonderful happens - like this Darwin sunset.