IRA basis during Backdoor IRA conversion question

I've gone through the FinanceBuff article and followed the steps to the T but the numbers are not adding up - https://thefinancebuff.com/how-to-report-backdoor-roth-in-turbotax.html

 

This table described what happened in 2019. 

 Traditional IRA ending balance as of dec 31 2018Traditional IRA account on (mar 31 2019)current year contribution to Traditional IRA (4/12/19)Conversion to Roth IRA (4/12/19)Taxable amountTraditional IRA Balance as of 12/31/19
Me11,164.2112,396.146000   
   18,396.1418,647.93251.790
       
  Traditional IRA account on (mar 31 2019)current year contribution toTraditional IRA (4/15/19)Conversion to Roth IRA (5/06/19)Taxable amountTraditional IRA Balance as of 12/31/19
My spouse6282.326978.426000   
   12978.4213173.6195.180
 
In the step 'Let's find your IRA basis', for the question - 'Total basis as of Dec 31, 2018', I entered "$11,164.21".  It says the IRA basis we transferred from 2019 is different from the basis entered. Include an explanation.
 
My 2018's Form 8606, item #14 (Total basis) says $5500.
 
I'm not sure what to do now. Is my IRA basis $5500 or $11,164.21? 
Help please - @macuser_22@AnnetteB6