not to worry at this point.... there is a 'settle up' section on the 2020 tax return.... you can get credit for both stimulus payments that you are eligible for through the tax return. It will appear on LINE 30 of Form 1040 and will increase your refund.
The IRS will not be sending out stimulus payments beyond Jan 15, 2021 (yes, two weeks) and expect anyone who has not received their payments to 'settle up' on their 2020 tax return.
does that help?