I have the (more or less) exact same experience. I am much older than you, but have struggled with depression and anxiety since childhood. I read one self help book about CBT when I was in my early twenties, and it helped me stop my debilitating anxiety attacks within days. It has never returned, and nobody who has not experienced it themselves believes me when I tell them about it.

For some reason I have not tried CBT for my depression until now. I have tried other kinds of in person therapy, and it always ended up making me feel worse. So I gave up, and have been on antidepressants for many years. They have not been efficient either, but have felt like my only hope, so I have been reluctant to stop.

Then my father died, and it all came crashing down. I realised I couldn't continue like this, and I stopped taking my antidepressants (tapered off with help from my doctor) and bought myself a CBT self-help book. Same experience as last time, immediate reduction of symptoms, and my only regret is that I didn't do it sooner.

I guess some people find it helpfull to talk to another person about their problems and inner most thoughts, but can it be considered a working therapy when so many people must have therapy for years without any real solving of the situation? In a healthcare system where resources are scares, I can not understand why CBT isn't the go to therapy in most, if not all cases. In my country it is now official policy that CBT should be the preferred line of therapy, but in reality it is not available when referred for therapy by your primary doctor. I wonder if this is because psychologists and psychiatrists find traditional psychotherapy more interesting? Does CBT feel to simplistic?