I have the same issue, as a child it was not as much as a problem except I had difficulties with un-intresting topics so my mind wandered quite a bit in class and such but I still did alright on school work and tests. I was able to heavily focus on intresting topics so I was pretty good with essay writing in middle and part of highschool. Then something traumatic happened and I ended up with PTSD, which I hate but since it will likely never go away I should probably try and learn to live with it or something. Anyways since then Its even hard for me to focus on things I enjoy or movies.

I know I dealt with a lot of unpleasntness as a child, so I am not sure my PTSD is from the one major event or if that was just the final straw but the other experiances like being ostracized by the other kids and some teachers could have factored in. I have considered the possiblity of ADD being part of it but I don't feel I quite fit the criteria and I haven't been diagnosed with it.