So far, so good! However, we still don't know which of the arrhythmias it is, and if it is atrial fibrillation or atrial flutter, you really 'should be' on a DOAC (Direct Oral Anti-Coagulant) such as rivaroxaban or apixaban. If you do have intermittent AF, also formally known as 'paroxysmal' AF, the greatest risk early in the development of it is a risk of stroke. The problem is that a fibrillating left atrium has a small 'grotto-like' lump on its extreme upper left that is called the left atrial appendage. The LAA doesn't flush itself out of stale blood quickly enough when its host atrium is fibrillating, and if a clot forms there and gets dislodged, which can happen at any time, including weeks later (!!!!), the clot can travel to coronary arteries, the lungs, or, egads!...to the brain. A most unwanted event.

Metoprolol is a 'rate control' medication that works to slow the heart and also to make its beat strokes less forceful. It happens to be also useful for people with incipient hypertension (high blood pressure) as a result of its action.

Finally, yes, as far as I know (I'm far from a cardiologist, or even a doctor), an otherwise healthy heart, no cardiomyopathy, no valve disease, no ischemia, is going to show a normal ECG when it is in sinus rhythm. It is when the electrical disorder happens that an ECG running concurrently will definitely show unusual waveforms.

If you take a look at Kardia, and decide you'd like to try one (they are good and have sold millions....and no, I am not 'involved, and only use a Galaxy watch), you can get a 'readout' downloaded from the device to you tablet or PC and take a look. If it's AF, there will be no P-wave and the distance between the R-waves, also called the 'R-to-R interval', will be quite clearly varied, some long, some short. AF is characterized as 'irregularly irregular' heartbeats.

This is a horribly long URL, but it's an example of what an ECG looks like for AF:
https://www.bing.com/images/search?view=detailV2&ccid=dOPF%2FGF5&id=F50BDF95F0407EF68AE1E22358CC3D32BC6BBDF7&thid=OIP.dOPF_GF5LOVkZ1qGhkvUVwHaCx&mediaurl=https%3A%2F%2Fwww.aclsmedicaltraining.com%2Fwp-content%2Fuploads%2F2021%2F09%2FACLS-Figure-30.jpg&cdnurl=https%3A%2F%2Fth.bing.com%2Fth%2Fid%2FR.74e3c5fc61792ce564675a86864bd457%3Frik%3D971rvDI9zFgj4g%26pid%3DImgRaw%26r%3D0&exph=560&expw=1495&q=what+does+an+af+ecg+look+like&simid=607992676649951713&FORM=IRPRST&ck=E161CC42AA92820B0C42730ACA137F9B&selectedIndex=6&itb=0&cw=2297&ch=1183&ajaxhist=0&ajaxserp=0

That is very common to have short period of an arrhythmia and then you see the doc and you are back in rhythm. The Kardia will record the event in real time. I am assuming you can feel it with it happens. Then you can send the pdf to the doc and they can see read the pdf that you send them. That way you are not playing wack a mole with running to urgent care or the ER and it is already back in rhythm. What kind of doctor are you seeing that is "at a loss" for what causes it? It is caused my any number of issues within the the heart. Some people have "triggers" that they feel starts the event but others do not necessarily notice any triggers.
A good cardiologist who specializes in electrophysiology of the heart is trained to find and understand the underlining mechanisms of what actually is causing the particular arrhythmia you have. There may be triggers that make people feel make it easier to identify but they as still prone to having Afib whether they can identify a trigger or not. Normal hearts do not go into Afib.