vent?

I failed my science class and i just started high school and i feel like my whole life and future is ruined and i hate my life and makes me want to commit i also suffer from adhd and it’s always harder for me to learn what do i do

It's so mad that it's summer. Year 10 went so quick but so slow. I'm so used to having time and it being "two years til our exams" and now its less than a year. I feel like I know nothing but I'm still in the top sets and do alright in exams but I still feel like I just don't know anything.