ADHD or simply concentration problem?

I'm aged 24. 1) I have lot of problem in organizing while meeting datelines. If a task exam is due 1 month/week, i cant comprehend the meaning of scheduling or sticking to the schedule. i cant grasp the meaning & fulfillment of "completing". Same for exam prep, and leads to chronic last moment rush. 2) in lectures/friend says something long &informative, i cant listen fully to the total version. Its "gapped" with several missing portions. when i read, sometimes i have to re-read 1 simple line many times. 4)i dont like & avoid to engage in tasks that require sustained mental effort. I do for 2mins, then distracted, again do for 2 min, so on. 5)forgetfulness is moment to moment issue. i often have my hands, arms filled with scribbles to remind me of stuffs to buy/bring/do. 6) i keep losing pen/ pencil when i sit to study. i also leave things behind, like umbrella/calculator/mobile in class. are these simply lack of mindfulness, procrastination, laziness or points at ADHD/ADD?