We cannot see your screen or your tax return. You lose the child tax credit when a child turns 17. And the child-related credits are affected in a big way by the amount of income you earned by working. If you earned a lot more--or a lot less--then your earned income credit would also be different.
Look at your 2019 Form 1040 to see the child-related credits you received
PREVIEW 1040
https://ttlc.intuit.com/questions/1901539-how-do-i-preview-my-turbotax-online-return-before-filing
Child Tax Credit line 13a
Credit for Other Dependents line 13a
Earned Income Credit line 18a
Additional Child Tax Credit line 18b
Child and Dependent Care Credit line 18d
https://ttlc.intuit.com/questions/1900923-what-is-the-child-tax-credit
https://ttlc.intuit.com/questions/1900643-what-is-the-child-and-dependent-care-credit
https://ttlc.intuit.com/questions/1899157-what-are-the-qualifications-for-the-earned-income-credit-e...
https://www.irs.gov/credits-deductions/individuals/earned-income-tax-credit/use-the-eitc-assistant
https://ttlc.intuit.com/questions/4499708-what-is-the-500-credit-for-other-dependents-family-tax-cre...
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
