I completely feel your pain. When I went through years of experiencing those headaches I could barely function. I had written to you earlier about how Botox had helped me, but I didn't know what your surgery entailed. I just wanted you to know my situation so you could compare yours. I know everyone experiences this differently and every doctor looks at this differently.
I had two surgeries and I did have duraplasty. I do have herniation still but the doctors think I have good CSF flow. And, therefore, do not believe further surgery is necessary. I have also had tethered cord surgery (which is common with chiari). This all left me with extreme, unending pain at the base of my skull. It then radiated throughout my whole body. I suffered for years. My only choice for relief was narcotics since I am allergic to any anti-inflammatories. So, when my Neurologist told me these were migraines that were going on for years undiagnosed, I was utterly baffled and truly did not believe her. But, she was right. I wanted to tell you a little more of my story to let you know that I really understand the pain you are going through. I hope that you can find an answer like I did.
Unfortunately, like you said, this process is a continual journey. You can only make the best decision for you at each moment in time with the best information available. Keep pushing for answers. We all have our story and a little piece of the puzzle. Hopefully, all of these little pieces of advice will help you find some peace.