beta blockers (metoprolol) are not really recommended as first or second line for hypertension in the absence of some other indication for them.
Historically in what order were you given your current medications?
A thiazide diuretic such as HCTZ or preferably chlorthalidone would be a logical next step. The definition of resistant hypertension is blood pressure uncontrolled on high doses of 3 medications, one of which is a diuretic. You could add one without increasing your pill count by either switching to amlodipine-benazapril (together in one capsule), stopping lisinopril and adding chlorthalidone; or switching lisinopril to lisinopril-HCTZ. You might even be able to dump the metoprolol. The diuretic should not radically increase your urination, you will just equilibrate at a lower circulating volume
I would discuss further with your new doctor.