Please do the research yourself, but it's my view that only a few in a handful really have ADD or ADHA. What you can do, is talk to your school counselor and or a doctor. Don't listen to what others say other than your parents, the school counselor and a doctor. You can get help, just don't be embarrassed and make sure you go for it.
please write everything down in bullet point. take your time and get clear in your mind what your main problems are then talk and show your list to your parent / guardian and go with your list to your doctor. you may also have depression. good luck!
You should seek some help from a school counselor. If you have already taken this step and nothing has happened you should contact your local Mental Health center- these centers are normally within the department of health and human service, if not they can direct you to where. Meanwhile try doing some centering exercises (like yoga) I know it sounds weird but it will help calm your mind and help enhance your concentration time. Also, if you are watching a lot of TV I would recommend you limiting that. The reasoning for this is that TV (especially half hour shows) train your brain to only concentrate for a few minutes at a time (think of watching a show. . .the show is on for 5-7 minutes and then goes to 5 minutes of 30 second commercials)