Modern low-temperature washes don’t kill bacteria, it needs to be above 60c to do that. Your armpits have their own bacterial “soup” which you can reduce by washing but you need a deodorant to suppress the bacteria that break down sweat to make a smell. Mitchum is excellent and unperfumed.
If you are stressed and sweating a lot, your pits will get smelly fast.
you tried an alum block? bought one for shaving purposes and at the time i read theyre good for neutralising odours, i think plenty of people use them for deodarants. just wet it and rub it well into your pits id imagine.