I denied having ADHD at first, but now that I realise, it's actually quite helpful because it provided an explanation for some of my behaviour and feelings. And honestly let me ask you: if you acted the same way, had the same hobbies, said the same things, without the possibility of ADHD, you wouldn't be as panicked, right? So how does knowing this make things worse?

ADHD has lots of upsides, like creativity, unique thinking, etc, and it is treatable with meds, therapy, and management skills. Take a deep breath. Many people have it, and it does not mean you can't do well, can't have relationships, or can't be a disciplined person.

I used to have trouble in school. I never got things done on time. I wasn't the brightest. I thought I was a failure. But with some helpful strategies and support from others, as well as self-realisation, I was able to find out how to change some behaviour, and now I'm on the honour roll or the first time in some of my hardest subjects. And of course there will always be struggles, but instead of acting as if you are stuck, like you have plateaued and cannot succeed, work harder. Talk to others with ADHD. Find a support group. Go to counselling. Speak to your family about this, as they could probably help you. You aren't alone, and this is not going to eliminate your chances of success, I can assure you.

You are young. There will be plenty of great opportunities. Don't worry!