Can't you just make an appointment? When asked what it's for, say it's a confidential issue. Or when the Doc calls you suggest you would benefit from a face-to-face meeting as you feel you need WB, weight and meds adjusting. Whilst they can believe the weight you tell them, most people would be unable to tell them their own BP.
I must admit I bought a BP monitor when diagnosed, as that's what actually opened this Pandora's Box. Raised BP was found when it was taken after and extremely unpleasant examination (No s*&% Sherlock, my BP was raised.......) Then white coat syndrome kicked in, then blood test to check kidneys,........................ Bingo!! Diabetes!!