In Feb, 2019 I made traditional IRA contributions for 2018($5.5k) and 2019($6k). Then I performed a backdoor roth for both in 2019. How do I acct for 2018 contribution?

You should have sent a 2018 8606 form with your 2018 tax return that has the 2018 non-deductible contribution on line 1 and 14.

You will be asked of you had and tracked non-deductible contributions - say yes. The enter the amount from the last filed 8606 form line 14 if it did not transfer. Then enter the total value of any Traditional, SEP and SIMPLE IRA accounts that existed on December 31, 2019.

That will produce a new 8606 form with the taxable amount calculated on lines 6-15 and the remaining carry-forward basis on line 14.

oops! didn't do that last year.  Thanks for the description.  this helped a lot