I had a hard time concentrating in school as well. Always in the principal's office, and got C's in conduct all the way through 6th grade. I thank god my parents never had me 'diagnosed' because I was guaranteed to be labeled 'ADD' and been prescribed medication for this truly bullshit condition concocted by the modern age.
I strongly suspect it isn't "bullshit" but it is overdiagnosed. It may be a very good thing that you weren't labelled and many may be mislabelled but that doesn't mean there aren't people with real neuropysiological/chemical differences that really do affect behaviour and can be counterbalanced by drugs.
Psychology has some of the worst 'science' there is. It's studying alchemy before understanding chemistry. Reading psychology journal articles is painful.
