Thanks for your question on Healthcare Magic.
I can understand your concern.
You have done almost all cardiac tests to rule out heart diseases except Holter monitoring (24 hours continuous recording of ecg).
This is must for the diagnosis of
arrhythmia (rhythm disturbances in heart).
Your symptoms like irregular heart beats, low blood pressure,
dizziness etc can be due to arrhythmia.
So get done Holter monitoring.
If this is also normal then no need to worry for arrhythmia.
Sometimes, uncontrolled stress and
anxiety can also cause similar symptoms.
So
consult psychiatrist and get done
counselling sessions. Try to identify stressor in your life and start working on it's solution.
You may need anxiolytic drugs too.
Don't worry, you will be alright. But first rule out arrhythmia.
Hope I have solved your query. I will be happy to help you further. Wish you good health. Thanks.