Hi anon and welcome!
Sometimes you have to be very firm with your GP before they refer you to a specialist. If the meds, courses, CBT and GP's diagnosis of depression aren't getting you anywhere then the diagnosis is probably wrong and the treatment inappropriate. What do you think you might have? I have a type of autism but I was misdiagnosed simply with anxiety and depression for years which made me suffer for much longer. Getting the correct diagnosis is crucial to understanding yourself and getting treatment/help that works.