The money added onto your balance each month is the interest that is charged by USAA for the credit that has been extended to you. That is how credit cards work. The only way the balance will be paid off quickly and with less charges is to pay more than the minimum balance each month.
Here is a good article about the costs associated with only making the minimum payment: http://credit.about.com/od/usingcreditcards/qt/minimumonly.htm
I would reach out to a financial advisor at USAA (or any other certificed financial advisor). They can help you figure out a good monthly payment that you can manage, which will hopefully reduce the interest you pay over the lifetime of the balance.