A few things:
1) any teacher in a current school in the USA should be able to point you to a guidance counselor or someone who can re-evaluate you.
2) I probably would have been diagnosed with ADD inattentive if they knew about ADD back when I was in school, so if you feel like you are unable to concentrate – whether you are officially diagnosed or not, your guidance counselor should help you.
3) A lot of the people on this forum are teachers, so someone smarter than me should be along shortly to help. : )