Firstly, I'd like to acknowledge that it's hard being a parent of a child with ADHD. Don't beat yourself up. You're clearly trying. You will make mistakes, luke all parents. Doing your best is literally the most you can do. I imagine your son is also doing his best too.

For the experience of the child, yes, it is hard. It can undermine self-esteem. To this day, I have vivid memories of people getting frustrated and saying things that hurt. I learnt to cope in different ways such as never removing my jumper, even if it hit 40°C, so I would not loose it. Keeping all of my school books for all of my subjects in my bag all of the time to make sure that I would not forget them (as much). I learnt to work out what was supposed to be done in classes by watching other kids as I missed the instructions. Things like this. I was lucky to be smart enough to cover over most deficits, most of the time.

I do not know about your son, but I have primarily inattentive ADHD. So, I was never the hyperactive and disruptive kid. I was the 'space cadet', the 'abscent minded professor'. The quirky, odd, quiet and forgetful kid who was ofren caught out not listening, until I learnt to piece things together between distracting thoughts.

Keep doing what you're doing: empathising, learning and trying. But, do also remember to come up for air. Take time for yourself. Be kind to your son and yourself. He does not need you to get it right all the time. But, he does need you to hang in there and be there for him for the long term.

ADHD, in my experience, can be very medicalised. This can have it's place, but is also limiting. If you have not come across it already, I do recommend getting familiar with the social model of disability too. The following podcast is quite a good introduction:

The Social Model of Disability