I diagnosed when I was like... 8 years old. From then to 17 I was on various meds, finally gave them all up. So for about 22 years I've coped with ADHD without meds. I am a Staff Engineer and make a good living, respected in my field.
Regardless of anything else, I think the key thing to remember about ADHD is that you do not need to be a high-performing human being, at all, in life. You will forget things and get distracted and not get as much done. So what. You are still intelligent and caring and dedicated and responsible and a hard worker. You probably put more effort in (when you get around to it) than many others without the condition. And you will do about as well as everyone else, on average. And this is fine. Do not put pressure on yourself to live up to what someone else can do. Only do what you can do, in your time, and be at peace.
Regardless of anything else, I think the key thing to remember about ADHD is that you do not need to be a high-performing human being, at all, in life. You will forget things and get distracted and not get as much done. So what. You are still intelligent and caring and dedicated and responsible and a hard worker. You probably put more effort in (when you get around to it) than many others without the condition. And you will do about as well as everyone else, on average. And this is fine. Do not put pressure on yourself to live up to what someone else can do. Only do what you can do, in your time, and be at peace.