Sorry, I didn't mean to imply that it's possible to treat ADHD with just behavioral changes or occupational therapy. That wasn't true in your case and it wasn't true in my case either. In my case, medication has been eye-opening and life-changing. When I went back to school, however, I also found it helpful to work with an occupational therapist to set up specific strategies for staying organized, keeping up with assignments, effectively using my studying time, and minimizing distractions. Working with an OT who understood ADHD was different from just trying to adopt general studying strategies and it really helped me succeed in grad school. If the parent poster is in university, an OT may be an available resource.
If I regret anything, it's not getting diagnosed until I was in my 30s. I wasted years of my life doing poorly in school, being depressed about it, blaming my performance on being depressed, and then dropping out of school. I eventually graduated, only 10 years late and with a 2.2 GPA. After getting diagnosed and treated, I went to graduate school and finished in the top 15% of my class with a 3.7 GPA. I think I've redeemed myself, but I won't get any of those wasted years back.
If I regret anything, it's not getting diagnosed until I was in my 30s. I wasted years of my life doing poorly in school, being depressed about it, blaming my performance on being depressed, and then dropping out of school. I eventually graduated, only 10 years late and with a 2.2 GPA. After getting diagnosed and treated, I went to graduate school and finished in the top 15% of my class with a 3.7 GPA. I think I've redeemed myself, but I won't get any of those wasted years back.