I have had similar symptoms for 4 years now - 'multiple ectopic' beats. Many others on this forum have had these pauses for years and years without incident. You can always ask for an ecg to reassure you.
Wearing a heart rhythm monitor will show you if a heart rhythm is causing your symptoms. The most likely explanation is ectopic beats (premature beats from your upper or lower chamber). Your doctor isn't concerned because you have fainted, no family history of sudden death, chest pains, shortness of breath, waking in the middle of the night short of breath, swelling in your legs, etc. In healthy people these sensation are almost never dangerous but they just don't feel right and justifiably cause some concern. Just tell your doctor that you are really worried about them and need some reassurance by knowing what they are. Your doctor will probably be willing to order the tests to confirm it. Your doctor is going by the assumption that they are very rarely dangerous and you don't have high risk features.
I hope this helps.