Retirement tax questions

Line 14 of my 2018 8606 was $5,500. So the taxable amounts work out to $17,897.40 - $11,500 = $6,397.40.

But it doesn't make sense to me why I would need to pay tax on the additional $5500. I think the basis I enter in Line 2 is not correct, but that's the Line 14 of my 2018. 

 

Instructions say to use the Total Basis Chart: 

IF the last Form 8606 you filed was for a year after 2000 and before 2019,
THEN enter on line 2 the amount from line 14 of that Form 8606

 

Thanks in advance