ADHD is not a death sentence. And knowing why your life has been difficult in the past can be cause for optimism. As others have said if you have become more depressed since beginning medication then get to the doctor immediately.
I am 69 and was diagnosed two months ago. Knowing why I have bounced around all my life (in relationships, jobs, and finances) has been a revelation. The anxiety and depression that I’ve battled for the last 12 years have lifted a bit and the meds I’m on now seem to help calm my mental hyper-stimulation.
I’m working on new coping skills and systems because, as you know, the old ones are lacking at best. I exercise regularly, journal daily, and maintain an attitude of gratitude. I still need to organize and schedule my environment, but I’m getting more done.
I have survived a number of terrible things in my life and know things will get better.
Hope this helps.