Often peoples' refunds are less because their employer withheld a different amount of taxes. If you changed jobs, had time off or made more or less money; these things can all affect whether your refund is the same as the prior year or different. 

Your refund is the difference between the amount your employer withheld from your paycheck and what is calculated on your return. You can preview your form 1040 and compare it to 2016. Go line by line and let me know where you find a difference. This is great to do to make sure you don't miss something, catch a mistake, etc.  

To do so...

1. Log back into your TurboTax account and click Take me to my return
2. In the bottom, left side bar, select Tax Tools and then click Tools
3. In the pop up window, under Other Helpful Links... click View Tax Summary
   
4. Once on your Tax Summary, click Preview my 1040 from the left side bar
5. Scroll down past the informational boxes and start at line 7 and compare to the first 2 pages of your 2016 form 1040. If you don't have your prior year return, you'll need it to e-file so it's worth trying to find it now. Otherwise, at least go through these two pages and check the total amounts to your W-2s and everything you entered. 

Let me know what you find...