I'm 21 and have had problems with angina-like pain all mylife. more recently, i have started getting palpitations and breathlessness. i have had ekgs, holter, echos, bloods and cardiac ct angiogram done. have i left any bases uncovered?

Angina: If after a that you still have chest pain it's likely not really angina and may be due to something else . Angina is 21 year olds is quite uncommon.

Look elsewhere: You seem hung up on cardiac causes but you haven't said anything about consultation with a gastroenterologist to look at your esophagus. Esophageal spasm can mimic angina and can even get better with nitroglycerin. You should also consider whether or not this is an anxiety or panic attack.

Not cardiac: Pretext probability given your age was incredibly low for CAD & incredibly thorough evaluation safely rules this out...Gi, musculoskeletal or anxiety could be other causes.