tachycardia, palpitation, mineral/electrolyte imbalance?

Hello :)
I am a female 19 y.o and ive been experiencing tachycardia and palpitation for years (also i have GERD, sleep apnea, spasmophilia, insomnia, respiratory problem, just to add information) but in earlier times its not this bad so evidently it got worse unfortunetlly which worries me. It could happen almost all day and i cant do normal activities. I dont know what i should do anymore and its really bad and frustrated me. The doctors did ECG, ECHO, holter monitor 24 hours, t3 t4 tsh tests but didnt find the cause. The cardiologist didnt really explain my condition only said tachycardia and gave me beta blocker but didnt really help much. And when i read about PAT, PAC, SVT, etc, i get confused because there are so many types which got me puzzled, which one i am.
I read about mineral defiency, electrolyte imbalance, hormonal imbalance have something to do with it. Because a lot of people said they experienced that and it has helped them.
But how do i know if i have this imbalance situation going on? And does the electrolye/mineral level change everyday in our body? Ive been on calcium, magnesium and kalium bloodtest but the result was in normal range. But i read on some websites when i was googling that the kalim and magnessium test dont always accurate.
Also i read that cayenne pepper and mother tincture would help but the other said the opposite which confused me.
If anyone knows any information related to it please help,
i would truly appreciate it thanks. :D

Yes, i know i will revisit my cardiologist to ask about it. My symptoms positively not due to reading the information because the reason why i was searching on the internet is because of the condition i am having, not the other way around. I wouldnt even google about health if its not because of the condition im having.