Can you tell me why i owe so much this year?

Usually more income = more tax = less refund.  Your withholding didn't increase enough to cover the tax due.  Or some credits you got are reduced because you made more income.

And the IRS changed the withholding tables so you got more in your checks during the year instead of a big refund.  Or there are other tax changes.  And any  dependents you have are a year older.  If you made more income that can reduce some credits you got like the EIC.  

Here's a good FAQ on why your refund might be less than last year

https://ttlc.intuit.com/community/refunds/help/why-did-my-refund-go-down-compared-to-last-year-s/00/25993

one other possibility is that you entered some number(s) incorrectly. review all your entries.