Hi, I'm not a professional but I feel like offering some reassurance until you're able to be given a more thorough talk by somebody else here.

I also have partial RBBB, which was found on an ECG 3 years ago by my cardiologist. RBBB can be either as a symptom of a problem, or be found simply in healthy people. I'm the second case, and I haven't shown signs of it since I've been under mental stress. RBBB on its own is of no concern. If physical symptoms or a diagnosis is made, this could CAUSE RBBB but it is found as a result of an issue, and is not in itself something worth investigation. However, as you've already been investigated, this is of no concern whatsoever, at least in my opinion.

The way in which you describe this issue seems to take on similar language to that of everyone else who suffers with cardiac anxiety. In fact the vast majority of posts here are indeed due to that very thing. The way you count your PVCs, describe it as ruining your life, and the fact that you seek to 'prove' what causes it by taking large deep breaths is typical of somebody who has a significant anxiety around their heart. Most people who have a cardiac condition choose to ignore it, and fixation indicates what is most likely anxiety. Take a look through the other posts, you'll find that the vast majority are people who self evaluate.

Having induced palpitations does not lead to sudden death. The symptoms you describe (taking large breaths resulting in these palpitations, and having some throughout the day and some in clusters) are typical complaints that most people here with anxiety disorder complain of. In fact, as far as the 'large breaths' test goes, I have exactly the same complaint, and I certainly haven't had abnormal heart returns.

My father also suffered with pericarditis and myocarditis. This was found in a routine exam. The issue was traced by his cardiologist to a case of pneumonia he suffered with in his mid-20s. More than 50 years later, it came back to bite him, despite him having been an athlete for the entire time.

As this was under monitoring, this was of no further complaint. Your cardiologist, also, will be completely aware of your physical state and will not take any 'risks' of you having an issue.

Keep on living your life, you won't suffer sudden death, nor any ill feelings by continuing. Don't monitor the palpitations, and make sure to eat and sleep at the right times of day, keep good posture and exercise well. These are the best ways to not only feeling better and escaping the general grips of anxiety, but will also help quell the palpitations.