Thanks for your question on Health Care Magic.
I can understand your concern.
Since your all cardiac and Pulmonary tests are normal, no need to worry for major heart and lung related causes.
Uncontrolled psychiatric illness like
depression,
anxiety etc can cause breathlessness.
So in my opinion, better to consult another psychiatrist and get done counseling sessions.
Counselling has a great role in psychological treatment along with drugs.
Try to identify stressor in your life and start working on its solution.
You may need newer psychiatric drugs.
So
consult psychiatrist and discuss all these.
Hope I have solved your query.
I will be happy to help you further.
Wish you good health. Thanks.