Have you looked carefully at your 2021 Form 1040? Did you go through the Federal Review section when you prepared the return? Was there an amount on line 30 of your Form 1040? If you had an amount on line 30 that is the recovery rebate credit--already included as part of your 2021 refund. If you really did not receive the 3rd EIP last year and do not have it on line 30, then after your 2021 return has been fully processed you can amend and use the recovery rebate credit to get the 3rd EIP payment of $1400 per person.
https://ttlc.intuit.com/community/tax-return/help/how-do-i-amend-my-2021-return/00/2544441
Even during “normal” times it takes about four months for the IRS to process an amended return. During the pandemic and due to the severe backlog at the IRS it is taking much longer—six months or more for many amended returns. Do not expect quick results from amending. When the IRS issues a refund for an amended return it will be by check. They do not make direct deposits for refunds for amended returns. You can watch for information here:
https://www.irs.gov/Filing/Individuals/Amended-Returns-(Form-1040-X)/Wheres-My-Amended-Return-1