Can u have low or normal blood pressure reading with gp but still have pulmonary hypertension?

Yes: Your systemic blood pressure and your pulmonary pressure are two totally separate things and one can easily be elevated without direct effect on the other. Pulmonary hypertension refers to elevated pressures on the right side of the heart involved in venous return from body and transfer of blood to lungs for oxygenation. Blood pressure you measure in your arm is pressure from heart to body.