The stimulus questions are asked in the Federal Review section of the TurboTax program. Any payment you were eligible to receive based on the 2020 Federal tax return but did not receive will be entered on the Federal tax return, Form 1040 Line 30 as a tax credit. The credit is included in the federal tax refund or it will reduce the amount of federal taxes owed.
But did the 600 show up on your 1040 line 30? You got the first one for 1200? The new 3rd one for 1400 comes separately. The IRS is still sending them out in phases. So don't worry about the 3rd one yet.