Heart beating weirdly. I'm worried

Hello doctors! In the last month my (M 23) heart has been beating in a weird way.

In irregular intervals it skips one beat and the one after is stronger and i can feel it in all my arteries (mostly in my throat) I've done an electrocardiogram during which the "strong beat" did not occur, here is the report:

Sinus rhythm: The heart is beating with a regular rhythm originating from the sinoatrial node.

Physiological sinus arrhythmia: A normal variation in heart rhythm.

Heart rate (HR) 71 bpm: The heart is beating 71 times per minute,

P wave, A-V (atrioventricular) conduction, and I-V (intraventricular) conduction within normal limits: The heart's electrical activation and impulse transmission are regular.

Repolarization within normal limits: The return to the resting phase of the heart is normal.

Normal Qtc: The corrected Q-T interval is normal, indicating that the repolarization time is regular.

ECG within normal limits: No significant abnormalities were found.

Other useful informations: - In the morning it seems to be less present - During heavy physical activities it seems to be less present - It can be one time per minute, or, like today, three times one after the other: normal beat, skip beat, strong beat, normal beat, skip beat, strong beat for up to three/four times consecutives. There's always (at least from what I've noticed) a normal beat in between. - I do not feel dizziness or shortness of breath when it happens - I'm a smoker - i drink only one coffee in the morning - I drink alcohol in the weekends. - my job is pretty sedentary but i try to walk at least 4 km per day and go to gym 2/3 times per week. - i do not have any pathologies that I'm aware of. - I'm not really stressed/anxious at the moment.

What could this be? Do you guys have any ideas? It started out of nowhere.

Thank you all!