It is unlikely that not showering every day is the cause of your yeast infections. In fact, if you have a good reason not to shower every day, such as dry skin, then this is a fine routine. It is actually much more common to have yeast infections as a result of too much cleaning. For example, applying personal cleaning products to the vagina, and especially douching, is probably the most common cause of yeast infections. This is because the products kill off the normal healthy bacteria that live in the vagina, allowing the yeast to proliferate unchecked.
Another common cause of yeast infections is from sexual intercourse. This may be because of a personal lubricant that has the same effect of killing off bacteria or it may be because your partners has yeast living on their skin.
Another very common cause of yeast infections is antibiotics. If you take antibiotics for another infection, as a side effect they will kill off your normal bacteria, and predispose you to a yeast infection.
In most women, yeast infections occur sporadically and are not a cause for major concern. They can usually be easily treated with over the counter anti fungal medications or with a prescription from your doctor