Did you each get IRS letter 6475 saying how much you got? They should have sent you 4,200 (1400x3) based on your 2019 or 2020 return. You should each each get a letter for half 2100. Did you claim your child on 2020 or 2019?
Double check your bank statements and Check your IRS account (both accounts if married)
Your Online Account | Internal Revenue Service
Line 30 is only if you didn't get the full amount or qualify for more.
