Really! Three years can feel like an eternity. You need to really let your doctor know that you want relief. If he is not willing to come up with a plan, find a new doctor right away. It's time to feel better. Your happiness is a very important issue. Deal with it. We are rooting for you and hope everything turns around soon. Hang in there.
No Toots, it's NOT just you. Millions of us out here suffer with the same issues, but the good news is that there is a lot of help for us. Therapy or therapy combined with medication can help you get to the root cause of your anxiety/panic. Once you figure out why it's happening, face it and learn to deal with it, you WILL get your life back. It takes work, but the option is to waste your life being anxious and afraid.
You've had a great many procedures done that have ruled out a physical cause for your anxiety, which should be a great relief. Now you need to think about getting into therapy to deal with what is making you panic.
What I find very difficult to understand is why none of the doctors you saw discussed the possibility of anxiety/panic and tried you on a benzo to see if that helped. To let you go on for three years suffering with this is quite lackadaisical on their part. You might want to think about a new doctor, one who actually reads medical journals.
I wish you the best of luck
Peace
Greenlydia