Traditional IRA to Roth Conversion

My situation seems simple but Turbotax doesn't seem to walk me through it in a way that makes sense to me.   

I am retired, have no W2 income and want to look at the tax implications/Brackets to determine what I can convert from traditional to Roth but from what I've been able to research this effort is commingled with contributions.

 

I receive $32k in SSA, and budgeted an ordinary distribution from my Traditional Ira  of $33k but when I increase the $33k to $53k TurboTax increased my tax liability by about $7,300 which doesn’t make sense.   Especially since I’m looking at the SSA tax Calculation, spreadsheet, and formulas that they provide showing that I am still in the 12% tax bracket?  

 

Is there a straightforward road map that I can follow to achieve a conversion and look at the tax consequences?

 

I very much look forward to your insight

 

Thanks