I'm in Canada, I just found a GP last year, and I told him that I thought I had ADHD. He gave me a bit of a survey type thing, which I answered honestly, and his assessment of my answers was that "it was consistent with mild ADHD" though, ADHD is more of a spectrum... I digress.

After that he asked if I felt it was impacting my life, I said very yes, and he got me on some medication which has significantly helped me.

IDK, maybe take what your shrink said to your GP, since your GP can still prescribe you the right meds to help you out. I mean, your old shrink said that you have ADHD, so if they're not doing anything about it, and you feel strongly about it, express that to your GP and they have the ability to do something, if they won't, start looking for a new GP at that point...

Your GP is supposed to help you to live your life and maintain your health, both physical and mental health. If they're not doing that job for you for day to day issues, then they don't have your best interest in mind when treating you, and honestly, that's stupid.

My GP is amazing, he listens to me and has no problem with giving me what I need to help out; some GPs need more proof or testing before taking action, which is generally fine, as long as action is taken at the end of the process, then all is well. If they still refuse to act then I have to wonder why they're even still practicing medicine if they're not willing to help you out.