You can use this interactive IRS tool to see if  your income works for EIC:

https://www.irs.gov/credits-deductions/individuals/earned-income-tax-credit/use-the-eitc-assistant

https://ttlc.intuit.com/questions/1899157-what-are-the-qualifications-for-the-earned-income-credit-e...

And do not confuse EIC with the child tax credit.  You cannot get CTC for an 18 year old--you lost the CTC when he turned 17.  Now you can get the $500 credit for other dependents for him.

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://www.irs.gov/help/ita/does-my-childdependent-qualify-for-the-child-tax-credit-or-the-credit-f...

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...