Vacantangel, you say that you stick to a very restricted diet, but don't consider it an eating disorder? Can you give an idea of what you mean by "restricted?"

If you're taking in fewer than 1200 calories per day on a regular basis, that's a sign of an eating disorder. And it's likely to be related to your low potassium.

If you're not eating a balanced mix of foods and nutrients, that's likely an eating disorder -- and very likely to be related to your low potassium.

If you're overexercising to keep your weight down, that can be part of the low potassium, and the eating disorder.

Drinking too much water can lower potassium.

Not eating enough fruit can be involved in low potassium.

Using laxatives or diuretics can lower potassium, and are a sign of an eating disorder...

I guess I'm belaboring the point, but I do hope you get some help. Good luck.