Wow, I have anxiety and I feel for you however I am medicated. Can you check the anxiety medications out there to see if one is suitable for your conditions. I've been on a few of the medications over time and there's a lot of different anxiety med's out there. I'm no doctor so I can't say if one of these works within your limitations, but I looked up one anxiety drug I've used and it is used to get people off Benzodiazepine's so I would think it is a different class of medication and might work for you.

I sit up front as far as possible and I use a window seat. I like to see and I'd like to know what's going on so I try to listen to the cockpit on IFE if possible on your flights. Some folks like the aisle but I'd prefer to look out at space instead of looking around at walls and people and such, the window and space helps me. And I try to fly tired, if I am more tired the easier it is for me. The visualizations and muscle relaxation techniques described by Boofer are great ideas, and I think we all use something like that to help our mind and body. This is going to sound crazy to most folks, but I also believe in and use Accupuncture for a lot of issues. One of them is my anxiety. So you might want to look at accupressure / accupuncture if nothing else works or is working enough for you.

But I know a few others and everyone has something else that works for them. There's unfortunately nothing to works for everyone. Good luck and my best wishes in overcoming this.