The stimulus payments are really based on your 2020 tax return (income, dependents, etc).
The IRS is using either 2018 or 2019 – whatever is available - to ESTIMATE that payment
When you file next year there will be a “settle up” section on the tax return.
If you are due more stimulus (and this would include where you are not a dependent in 2020), you will receive it through the 2020 tax filing as an additional refund
If you received too much stimulus (not the issue here), by law , you are not required to return it
