FF, I really do not have any unreasonable levels of anxiety, but I will share some thoughts in hopes you may find one or two things that help.
First thought comes from over a couple of decades ago when I was a Pre-med college student (before switching to bio-medical engineering). I had a physiology professor suggest we learn about vitamins and minerals on our own, because we would not acquire that in med school. I remember wanting to test some of the stuff I read, and one summer taking classes, started taking zinc, B complex and C vitamins to see if I would have any less test anxiety. After a couple of weeks, it made me TOO relaxed, I did not want to study for the test, and discontinued testing. I pulled up a couple of links that may, or may not be helpful (similar to some of the others' suggestions) for vitamins.
Also, having had others work for me over the years that had this issue, I usually tried to make sure the person was situated as best possible to be productive without having to under go routines of high stress events that may trigger an attack; and assign high stress events to others who love it, because they love to fight fires. Hopefully your boss is thinking along those lines. A lot of employee job success is how the employeer sets up the job conditions for success. Good bosses think about the environments, tools, tasks, and processes to achieve successful results without over burdening the human in the equation.
As has been pointed out, what anyone fears, plays a large part of how anyone (with or without anxiety) live their lives. You might try reading a book or two like The Science Of Fear, or looking up youtube on John Stossell investigations where he talks about public fear. Most things people fear, are stastically very rare to ever occur, and we waste energy on fearing them.
Also you may want to do a personality profile on yourself. You can do these on line for $50 to $120, one service has both DISC and Myers Briggs tests. I have used these folks before for testing : http://www.thediscpersonalitytest.com/ . Workplaces that do use them, use them to help everyone understand we may all hear the same sentence someone is saying but have a lot different reactions to the same information. An example: Someone that works for me now, has anxiety attacks, occasionally leaves meetings when he feels attacked or frustrated, although the rest of us heard an "informational sentence", he heard an attack or unreasonable deadline. He has a high C component in his DISC profile, which translates as he is very conscientous of his work, a hard worker, feels he "HAS TO" "check off lists", and does not like to be questioned about anything that may even hint of a performance issue, because he is giving a strong effort (regardless of results). Using the test results and study hints for working with him, I can try to address his fears or phobias, and still work with him for best results.
I don't know if any if this helps, but FYI. Hope you find what you need.