Hi. That's a lot to deal with from such a young age. You are asking for help which in itself is great. Our past has a lot of influence on us and who we are as a person. We need to resolve it and move forward with it.
I would suggest you to see a psychologist who will help you understand yourself and deal with the past and will work on your concentration issues.
Next Steps
See a psychologist/therapist. My organization and I are more than happy to help. (themindresearchfounfation.org)
Health Tips
Don't just brush it off as a trivial problem, these are things that shape us as a person and a little help from someone could go a long way. Good Luck !