I get fast heart rate all the time not always over 100 but I have had stress echo a ECG a holter monitor and bloods and all was normal so what is causing it as heart is healthy??

Tachycardia. Do consume coffee, tea, energy drinks? ANY caffeine containing food or beverage can cause tachycardia or rapid heart rate. Do you take any medication. Also consider tobacco as possible cause. Assuming your thyroid function and other labs were normal. And. If all fails you might need to a Electrophysiology (EP) cardiologist.
Benign Tachycardia. You have benign Tachycardia which really means your heart rate is higher than normal without any thing wrong with your heart and other systems in body You are being treated correctly with beta blockers Prpranolol You should avid caffeine and energy drinks and follow with your doctor and do not worry as that can raise your heart rate as well.