Why do I owe money? How did I not set aside enough of my income for taxes if I have no control over it?

you can increase w2 withholding. ask your human resources. they will help. alternatively just write a check. 

There are a few factors that determine the size of your refund. As jjgrmMD mentioned, your HR department can help with withholding from your wages.

Here is a TurboTax Help article with more information about your refund.

@sophiabullington

https://www.irs.gov/individuals/tax-withholding-estimator

https://www.irs.gov/pub/irs-pdf/fw4.pdf