After you file

First the IRS is not always correct ... the "you MAY be eligible for the EIC" is just to alert you to the possibility.  If you entered the child into the TT program correctly then the proper EIC would have been populated automatically.   Before you do anything ... make sure your original return was filed correctly ... save a PDF of the return and review it carefully.  Next, was the original refund ever issued ?   Until the original return has been fully processed you should not amend the return even if someone at the IRS said to do it ... putting an amended return into the mix prematurely can delay things even longer.