If you did not get the full amount in advance you can apply for the balance as a credit on your 2020 return using the 2020 income to qualify. Sounds like you don't qualify for all of the missing money. Review the worksheet to see how the program came to that amount.
You can peek at only the Federal form 1040 (and Sch 1-3) and the summary of the state info by going here:
1) lower- Left side of the screen...click to the left side of the "Tax Tools" text selection.
2) then select "Tools"
3) then select "View Tax Summary" from the pop-up
4) then back to the left-side and "Preview 1040"
Then hit the "Back" on the left side to get back to your tax entries.
To view your entire return using the online editions (including the state) before you file, you will need to pay for your online account.
To pay the TurboTax online account fees by credit card, without completing the 2020 return at this time, click on Tax Tools >>> Tools and then Print Center. Then click on Print, save or preview this year's return. On the next page, to pay by credit card, click Continue. On the next screen it will ask if you want Audit Defense, if you do not want this option just click on the Continue button. The next screen will ask for all your credit card information so you can pay for the account.