If you were claimed as a dependent in 2019 but not in 2020, you can still get the Recovery rebate credit on your 2020 return even if your parents got it for you. And actually if you were over 17 in 2019 they did not get it by claiming you as a dependent. They only got it for dependents under 17.
So you should have 1800 on 1040 line 30 for the Recovery rebate credit. 1200 for the first round and 600 for the second round. Where did you come up with 2,400? Are you married?
I don't know about the new 3rd one for 1,400. That isn't included on your tax return now.
