It may not have actually been sent. Did you get a confirmation e-mail saying the IRS had accepted it? If not, go to the IRS portal and register there ("Non-filers: Enter Payment Info Here"). If they say you have already e-filed, then use the other IRS link ("Get My Payment") , and enter your bank account information there.
I read two descriptions elsewhere about people who had prepared 0 income returns to mail in with TurboTax, and later they logged in to TurboTax todo stimulus registration. The system just said they just sent the info to the IRS, without prompting about payment options (account numbers, etc.) It turns out, in those cases the registration was never sent. Those people were able to register at the IRS's portal.
