One of the main concerns with diuretics is loss of potassium. I assume you won't be taking the medications for long periods of time so it shouldn't be too much of a concern.
Triamterene is a potassium sparing diuretic which will help you keep potassium in your body. 37.5 mg is a lower dose for triamterene. hydrochlorothiazide will cause you to lose potassium so essentially your levels should not drop. 25 mg is the normal dose for hctz. There are stronger diuretics out there so these are not "too high."
If you are worried about lowering your BP, just watch for signs of dizziness, especially with prolonged standing or when you change from a sitting/lying position quickly up to a standing one. If you feel faint, you may want to discontinue the medication. Diet is important, food in Mexico may be causing you to have greater than normal salt intake which will cause swelling, so just be cautious of your diet. Also the medication will most likely make you want to pee a lot. Don't take it too close to bedtime or you will be waking up to pee!
Ordinary vitamin C is a diuretic. If your feel swell get the crystaline kind and take about 1400 mg a day in two divided doses. Above that you may find yourself with loose bowels. Your physician should have recommended this first.
Get yourself a blood pressure cuff.
Avoid salt, which causes fluid retention.