I totally agree with greenlydia's response. Therapy and med's to control the symptoms will be beneficial and you will feel better, as far as the Anxiety goes.
Unless they suspect you have orthostatic hypotension, having you lay down to take your blood pressure is not "wrong." I suspect your BP goes down when you go to the ER because you now feel "safe" with all those doctors, nurses and expensive equipement around to help you in case something "bad" happens.
You say you not only have anxiety, which the Xanax will help, but you also state you are bi-polar and have OCD. That is a lot to deal with and I suggest, strongly, that you get yourself into some therapy to help you deal with those issues.
If you can't afford it or do not have insurance, ask the ER people to get a patient advocate for you. All hospitals have them on staff. They should be able to help you get the help you need, which is more than some Xanax!
The only technique that is going to help you is therapy and the appropriate medications.
I wish you the best.
Peace
Greenlydia