forget about deducted contributions to IRA , that doesn't matter to form 8606
It sounds like you made a non-deductible contribution in 2016 and 2020, and those amounts are all that goes on form 8606, assuming 2020 amount was designated for 2019.
If you convert all your current value to Roth, which is what you seemed to intend, then your IRA balance will be zero and closed out.
There's nothing unusual about that.
