@seamyb the only other things I can think of is Calcium and copper. Calcium deficiency and copper deficiency also caused me to have palpitations.
If you are taking b12 and B6 that can drive calcium lower and there are many things that can drive copper lower.
This website is helpful for looking at symptoms of deficiency and toxicity:
https://acu-cell.com/index.html
Under the conditions tab at Acu-Cell there's this:
Arrhythmia / atrial fibrillation [1] (irregular heart beat): Low magnesium, high /
low potassium, low copper, low Vit E, low folate, low w3 EFAs, low CoQ10, low PABA, high/low calcium, high/low zinc, high/low sodium, high iodine, high alcohol, autoimmune diseases, viral / bacterial infections, allergic reactions, recreational stimulants, heavy metal toxicity, intolerance to dental materials, spinal misalignment T4, T5 or T6, [opt. taurine, L-arginine].
and this:
Palpitations (pounding pulse without exercise): High iodine, high Vit B1, high Vit B6, high/low Vit B12, low PABA, low Vit B2, low calcium, low magnesium, low iron, low potassium, allergies. (see also "
Arrhythmia").
There is also a condition called arrhythmia with postural dependency so you might want to look into that. I know that my palpitations can be somewhat dependent on my body position. For instance, when I have them at night it happens when I'm lying on my left side.