Hi Lisa,
Just a quick note of how much I understand what you're going through. I've been sick for 16 years and because they can't find the biological basis for it the doctors that see me in the hospital try to say it's a psych thing. Never mind the two doctors who've seen me all these years say differently. So, yeah, I get it.
So, as for you my dear, there is something that comes to mind regarding your symptoms that you might want to have considered. It's call vocal chord dysfunction (VCD) I can be caused by anxiety, anxiety definitely makes it worse. People may often be thought to have asthma but upon all the testing (PFT's and the like) its all negative. Then they find out they have a VERY treatable thing called VCD! You can see a speech therapist who can help you relearn talking and breathing techniques and teach you interventions to mitigate they symptoms and get you back to being focused on living rather than whether or not you're going to stop breathing or not. Whew! What a relief it would be! Huh?
So, the thing is, a lot of the anxylitics are actually addictive. Things like klonopin, xanax, and I think even ativan, can be physically addictive, as well as psychologically addictive. Addiction can run on both sides of the gamet. The body may become physically dependent on a drug, but the mind can also become dependent. So there can be a double whammy. That said, frequently, various classes of antidepressants are often used to very successfully treat mild anxiety. (It doesn't take much anxiety to make one feel that one can't breath!) The beauty of the antidepressants is that they aren't addictive! Ones like the class called tricyclic antidepressants are particularly useful in this area. There may well be some newer classes that I'm not aware of. But the tricyclics are oldies but goodies, as the saying goes.
So in short, the antidepressants might be a good interim treatment to help you get through until you can figure out what's really going on!
Just remember, you can always get a second opinion, but you have to be careful about that. Because if you look long and hard enough, you'll eventually find a doctor to treat you the way you WANT to be treated, rather than the way you NEED to be treated!
I hope this helps. From what little I can gather, it sounds to me like you're doctors actually on the right tract!
Hope you feel better soon!