I was sub 2.5 GPA person throughout career. But I started learning things that interested me. Got more and more good at it. And somehow got somewhere. It's not a bad life but good enough.

Throughout my life I felt like what your are feeling right now. But I would say things eventually fall in line of you are persistent enough. It may take some extra time but it will.

Regarding ADHD, I would recommend you see a psychiatrist and follow your routine properly.