also look into the possibility of something called phenocromcytoma. Im not to sure of the spelling, but it is a tumor on the adrenal gland good luck
My mother suffers from very high blood pressure, also. For years hers ran at about 180/120, and although she took many medications, the doctors didn't seem too concerned about it. Last year it went to 230/140 and the doctor still just checked her every week and changed her medications, with no success. Eventually her son-in-law insisted that she go to the hospital, and they had a kidney specialist come in. (At the hospital, the ER doctor said if that bottom number is 140 or higher, it needs to be brought down RIGHT NOW.) The kidney specialist is now in charge of her meds and her blood pressure is 150/110. My mother was also pretty pessimistic that there was any medication that would lower her blood pressure, as she thought she'd tried most everything there is. So I am just adding another plug for the doctor's answer--see a specialist, even if your own doctor doesn't seem too concerned.
Part of controlling blood pressure with multiple medications is just a matter of trial and error - that is not unusual. However, when I need to use 3 or 4 medications to control blood pressure and still do not get a great result, I evaluate for other causes of high blood pressure, such as kidney disease. If your blood pressure remains elevated, you may want to see a high blood pressure specialist. In some communities, this would be a cardiologist, or an endocrinologist or a nephrologist (kidney doctor).