Without knowing your income, deductions, and other circumstances, it is impossible for us to say for sure whether or not you will get a refund next year at tax time.
However, if your income is relatively low, it is entirely possible that you won't owe any taxes at all, even if you haven't had any withheld. For example, in 2015, the standard deduction for Head of Household is $9,250, and exemptions are $4,000 per person. So with just the standard deduction and exemptions, your first $29,250 of income is tax-free. Other credits (such as the Child tax credit, Child and dependent care expense credit, and Earned income tax credit) can push this tax-free number up even more. In fact, it is possible under certain circumstances to get a refund even if you haven't had any income tax withheld.
If you make substantially more than that, and you are concerned that you aren't having enough income tax withheld, it may be worth your time to estimate what your taxes will be. Grab a 1040 form or some tax software, enter in guesses for what you think your income will be by the end of the year, and see what it says you would owe for taxes. If you think you will owe taxes, set aside some of each paycheck between now and the end of the year so that you will be able to write that tax check without a problem.