Sorry if it's too long. The main question is two last paragraphs.
Since I went to school I finished my schoolwork and homework very late. (I remember the teacher of my first year didn't let me go out on break times and forced me to finish my schoolwork.) I made (and make) unconscious mistakes in my exams. My grades were excellent till 7th year of school and then I started to regress in math as geometry entered into our lessons. I was awful at geometry in high school and it was my lowest grade.
As I entered in college my problems increased. I can't pay attention to the class and this caused me to fail some of my courses.
Sometimes when people talk to me I miss some words and sometimes I react or say something unconsciously.
Also another serious problem that I have is scheduling. I can't do my tasks according what I have scheduled. I always finish tasks later than what I've scheduled and sometimes miss some tasks.
Also I'm poor at finding my path in new places or places which I rarely go. There I usually go wrong ways!

Concentration, scheduling and finding my path
I really need help about these problems. I don't know that I might have ADHD or anything else.
Also my brother have concentration problems. My mother always blame him and punish him by preventing him from playing video games watching TV ,etc. These things recall me my past years and punishments which were harder for me.
I'm feeling that I'm useless and I wont be able to continue my education. I'm really loosing my hope in this life.

I'm sure you'll say consult with your psychotherapist but my problem is I frighten to do that. I want to make sure that I've a serious problem or not.