Since your Roth contribution was only $5,500, you only could have recharacterized $5,500. Perhaps you did recharacterized only $5,500, resulting in a transfer to the traditional IRA $6,906 after being adjusted for gains. That should have resulted in your 2017 tax return reporting a $5,500 traditional IRA contribution either as a deduction on 2017 Form 1040 line 32 or 2017 Form 1040A line 17, or as a nondeductible contribution on 2017 Form 8606 resulting in your basis appearing on line 14 to carry forward to line 2 of your 2018 Form 8606.
In 2018 TurboTax, simply report the Roth conversion by entering the 2018 Form 1099-R and indicating that you moved the money to another retirement account and that you converted the money to Roth. Then click the Continue button on the Your 1099-R Entries page and confirm that your basis in nondeductible traditional IRA contributions for years prior to 2018 agrees with what appears on line 14 of your 2017 Form 8606, if any, and that you've entered your 2018 year-end balance in traditional IRAs, if any. 2018 TurboTax will prepare Form 8606 to determine the taxable amount of your Roth conversion.
