Hi, Ken . . . I know exactly what you are going through. I changed doctors in August and she tested both of my arms only to find me at the 140/90 range. I told her I had white coat hyptertension, so she suggested I do something for her on my own where I would not be under stress.
If you have access to a home blood pressure monitor, you should take a reading in the morning before you eat (eating can raise your blood pressure, too) or go to a drug store that has the free blood pressure machine you can use. Do this for three or four days out of a week and give your doctor the readings.
If your readings are normal, they will place them in your chart and note what you said about white coat hypertension.
Best of luck!