Don't listen to the doom and gloom speech. An old slogan was once if at first you don't succeed, try, try again. Some seem to believe its now, at first you don't succeed, diagnose yourself and blame the illness. Being a perfect student takes practice. I entered high school with that goal and tried so hard and had so many mishaps. Just a few weeks ago I forgot a LOT of assignments at home and got half credit, it brought my grade down from an A+ to an A-. It happens.

Years earlier such mistakes where more common. As you get used to giving it everything you have, you get better at it. You'll get better at remembering things, it takes time. Trying as hard as you can is a skill that can be improved upon. You don't need a reward system, you don't need a notebook or anything, and you don't have ADHD. People with ADHD couldn't even commit to attempting to use a notebook, let alone being able to devout 80% of their time to any task. Be confident in your abilities, and use your anger and frustrations to fuel your further efforts.

Good luck.