You should be making your own kefir and drinking lots of it every day, several times a day. Remember that kefir can cause die-off so start with a small amount if you’re not already using it.
Two billion CFU’s is an extremely small amount considering that you’re fighting a Candida infestation. I would work up to taking as many in a 24 hour period as you can afford to take. And if you can’t find anything containing higher amounts, you should at least try to feed the bacteria as much as possible to be certain that they survive and multiply. I would suggest purchasing pure spirulina and taking it every day as a prebiotic to ensure that you are feeding the bacteria enough. Be careful when you first start taking this because it can cause die-off symptoms, and they can be pretty severe with spirulina.