Uncontrollable HTN in Young women

I was diagnosed with HTN at 22 yrs old, it seems to be a downhill battle.  I am fixing to be 24 and we are still having problems controlling my blood pressure.  My blood pressure had maintained within normal limits for about 6 weeks this summer with medicine changes and then started going back up.  I have lost nearly 22 lbs, changed my diet, began walking regularly, and don't know what I need to do next.  I have had several tests done and nothing seems to show anything, and I have had to restart a second medicine recently ANY SUGGESTIONS?.

[Cleveland Clinic]

I am assuming these tests are looking for rare causes of secondary hypertension. If negative then you will need a second medication and possibly continued weight loss to prevent the deleterious effects of longstanding uncontrolled hypertension.