I agree with Louise about the potassium supplements.

Florinef is a substitute for the hormone aldsoterone, which people with salt-wasting CAH cannot make.  Aldosterone helps you to retain sodium, and lose potassium.  Without aldosterone, you would tend to do just the opposite....lose too much sodium and retain too much potassium. 

CAH patients take Florinef because---without it---they would retain too much potassium, not too little.  Therefore, it would seem counterproductive (if not downright dangerous, in certain situations) to be taking potassium supplements, if you have CAH. 

I would question your doctor again about this.  Good luck.