Your doctor is right! Wait for the appointment!
The most likely diagnosis for what you are feeling ar your age is premature ventricular contractions (PVC's) or premature atrial contractions (pac's).
Both are normal in most cases. In fact everybody experiences them! Unfortunately most people don't feel them when they happen. Others.. Such as yourself were born with the unfortunate curse of being aware of them.
Cardiologists do have a tool that you can wear called a 'holter monitor' that will record your ekg for 24 hours.
They will then be able to diagnose you with pvc's or pac's, and possibly diagnose you with medications that will help you have less of them, and notice them less often!
They will also be able to compare how many pvc's you have every day with how many a normal person is expected to have and determine if you are having too many.
As for your left bundle branch block.. Thats a bigger problem! It is likely not directly related to your pvc problem, but depending on the exact nature of the bundle it can be a very concerning sign of future problems.
In order to assess the bundle branch properly some information is needed:
1. Is it "complete" or "incomplete"
2. Is it isolated or does it occur with another type of block?
3. Is it rate dependent (only occuring at high heart rates) or constant?
The left bundle branch is 3 times thicker then the right bundle, and it is incredibly resistant to changes in the heart.
Having a left bundle branch block at 19 needs a more thurough battery of testing to assess your heart structure for birth defects and genetic problems (echocardiogram required).
You need a thorough exam, history, maybe even a stress test!
Having a left bundle branch on its own is not necessarily a life or death problem, but given how thin and fragile the right bundle is, as well as your age and considering how much the heart naturally deteriorates as your years progresss, it is a feature that requires survey.
If the doctor that read your ekg was mistaken however, and the problem you have is a right bundle branch and not a LEFT bundle branch, the finding is normal.
If confirmed, I would anticipate biannual exams in the future.
It's complete! But I feel fine despite of the anxiety provoked for not knowing where those pvc/pva came from. They said everything was fine and that yeah, I'd have to check every couple of years the cardiologist.
I still feel breatheless, but I don't have anxiety anymore. Neither do have PVC's.