Just imagine if these diagnoses existed in the day of Einstein, he would have been medicated into mediocrity instead of making the impulsive observations and leaps of association he made. Physics would have been somewhat diminished if that had happened. Then look at people like Steve Jobs and Richard Branson and take heart from the "Think Different" campaign that Apple ran so many years ago!!!
I am 56yo and have always had a low boredom threshold (isn't AD/HD a euphemism for this??), have been an overachieving baby boomer as my doc calls me, and used to wonder what I would do with the strange and eclectic set of knowledge, skills and understanding I had acquired over a lifetime - including my impulsivity that was based, I now understand, on a very finely tuned iNtuition, but made no sense to others without those preferences.
I have been a lecturer for 16 years now and love it and use all of my accumulated and eclectic collection of skills and knowledge, and my curiosity, to forge new roads and methods. My industry, digital graphics and the technology, typography and corporate style, change so frequently I don't have time for my low boredom threshold to kick in, and I am paid very well.
Be true to yourself, follow your passions - you DO NOT have to adhere to other people's norms to succeed in life except where they are legally or socially unacceptable. Even then, if you believe them to be wrong, arm yourself with knowledge and understanding and push to change them.
Don't EVER let anyone make you feel less than you are because of their expectations!!