This is Dr.Suleman resident cardiology in cardiac rehabilitation
Your History suggest you had Heart disease
before. Heart cath means you got some blood vessel blocked . Due to that reason heart become weak than normal people and it cant pump blood effectively and fluid accumulate in lungs. and cause shortness of breath
I suggest you to do ECHOCARDIOGRAPHY
which will check your heart function. This is actually Ultrasound of heart and we can see your heart is pumping normally or not. if it is not working properly then doctors will put you on heart failure
drugs and all of your problems will resolve.
So summary is just see a good cardiologist or heart failure specialist and get an ECHO and see your heart is working fine or not. If your heart is all normal then go and see a pulmonologist.
Hope that is answer to your question :) Please rate question helpful if it helped you :)