I do feel your pain. I have such a similar story. I too was diagnosed in my early 40’s with ADHD/OCD after my young son was diagnosed. He was evaluated, and we went through a few psychiatrist’s and finally got him on the right therapy and meds. It was through that innate advocacy that any mother would do for their child, that led me to getting the right diagnosis for my son AND, it was through that process with my son that I realized there was a name/disorder for everything I had been feeling, reasons why I had such trouble in school, disorganization, feeling overwhelmed with everything I did, since I was a young child. The good news is that there is help for you, and through compassionate and consistent therapy, a complete diagnosis from a psychiatrist that is knowledgable with ADHD and/or other anxiety disorders, you will get relief and help for yourself.
As you advocated for your son, finding out what his potential issues were, please advocate for yourself. You are worth it and do not let any GP tell you otherwise. If something does not feel right to you, and you have reason to believe that you may have ADHD based on behavior and feelings you have felt for years and they match closely to what you have read, please find help for yourself. Don’t stop till you find it. You deserve to feel peace of mind and to have access to all the tools out there to help you live the best life you can. Good Luck and remember, you are not alone.