It is allowable to use your 2019 income if it results in a larger EITC for 2020. This is a change in the rules due to the pandemic legislation. Since it is already filed, a specialist cannot look it over unless you want to file an amended return.
Try viewing the PDF to see what amount was reported on Line 1 of Form 1040. Look in the top left hand and bottom right hand corners for the form number. If the Line 1 number included Form W-2s from 2019, you must amend(change) the return. Otherwise, the 2019 details would have only been used to determine the Earned Income Credit. Unless there were other errors, there would be no need to amend(change) what was filed.
For more information, see: What are the qualifications for the Earned Income Credit (EIC or EITC)?
