The W-4 is 4 pages even though the employer only needs the front page. Pages 2-4 contain instructions and worksheets you need for your specific situation. Depending on your expected income, and whether or not you will claim the child tax credit (or allow the other parent to claim it using form 8332 under the terms of your divorce order) your correct number of allowances might be as high as 10. Claiming fewer allowances than required will result in a larger refund.
This online calculator from the IRS will also give you an estimate of your refund (assuming your weekly or monthly pay for the rest of the year is about the same as it has been so far) and will give advice on how you can change it to increase your take-home pay and lower your refund. https://www.irs.gov/individuals/irs-withholding-calculator