The potassium thing usually happens when people are severely anemic. Potassium is robbed by developing red cells..they contain alot of it. But if you are not anemic then you would not be making the red cells so fast, and hence your potassium levels would not stressed that way.

In US 400 is the new low. But in Japan it is higher than that even...at 500-550. So consider your level, marginal.

Fabric softeners are problematic. I'd avoid them completely.
I never use them here. In fact we double rinse all our clothes.
You'd be amazed how much soap is left in after one rinse!
We use Tide Sensitive in fact.

If fragrances bother you, you might want to take some B1, or it improved version Benfotiamine daily. I've read that people with chemical sensitivities who react to aldehydes which are in fragrances, have a metabolic problem metabolizing aldehydes.
This would go for beer and wine and aged whiskeys too.
B1 is the cofactor in aldehyde metabolism.