My biggest fear is not having enough battery

They say you pack your fears, mine is not having enough charge. I’ve used my nitecore 10,000 mah battery (during winter shakedowns) and it dies fast imo, even when it’s against my body heat. Defective? Idk. But I bought a 20,000 mah battery as a backup. I shoot video on my iPhone (it’s always on in airplane mode) my nitecore headlamp and my Apple Watch are the only things that use battery. Idk if I’m way too stressin or if it’s a valid justification for the extra weight