Just remember that is you are diagnosis it will be like a door opening. I was a kid when I was diagnosed. From what I've been reading it seem psychologist are more open today to diagnosis an adult as ADD/ADHD or there seem to be another (possbliy a new name for the inactive AD|HD) a friend of mine found it EFT (Executive Function Disorder).

Plus, from what you are saying sounds very much like how most adults find out the have ADHD. If they decide to medicate you be open to try anything but be mindful of side effects and things that you think are just not normal. Don't let them say things like "it has worked on almost everyone I treat" or not listen to you because that is what get most medicated people into trouble. Plus, you should find a psychiatrist who will listen to you when you tell them if you feel wiry of drugs and that you wish to stay away from them.

You can function not medicated as you have for years but if you need that help then you need it.

Good Luck