I think the main problem is you are saying "no" to the question whether you made any non-deductible contributions to your IRA, and if you also missed this in 2023 then your Form 8606 will not be showing any 'basis' for the IRA to carry over from 2023 to 2024. Without any basis, your IRA will be reflected as all "pre tax" money and any withdrawal from it will be taxed. The premise of the backdoor Roth is that all your IRA is "after tax" money and the withdrawal from it is there not taxed (or taxed very lightly if you have earnings that accumulated between contribution and conversion e.g. if you contribute 6500 and convert 6504.47 you will pay a little tax on the 4.47 earnings).
Based on what you are describing I think your basis in the IRA from 2023 would have been 6500.
Go back thru the Traditional and Roth IRA section, say yes to "any non-deductible contributions to your IRA" and the next screen will ask you for the basis as of 12/31/23. Put 6500 in there and then answer the question for the value of your IRAs as of 12/31/24 (in your description you said 3.56 in step 10 but 7000 below it - sounds like it was 7000).
Then go back thru the 1099-R questions again just to make sure everything is consistent.
You will also need to file a Form 8606 for 2023 I think, but you can just mail that form in alone if it was just a contribution missed for 2023 and no tax impact you don't need to refile your 2023 taxes - see comment at the end of help page below.
See this help page for the steps https://ttlc.intuit.com/turbotax-support/en-us/help-article/retirement-benefits/enter-backdoor-roth-...
Not a CPA/Expert just my 2 cents how to proceed based on what you've described, hope this helps.
