Paying the TurboTax fees does not file the tax return.
To access your current or prior year online tax returns sign onto the TurboTax website with the userID you used to create the account - https://myturbotax.intuit.com/
Scroll down to the bottom of the screen and on the section Your tax returns & documents click on Show. Click on 2018
What is the status of the 2018 tax return? If the status is anything other than Accepted then the tax return was not e-filed. If you did not print and mail the federal tax return then the return was never filed.
Click on Download/print return (PDF)
A 2018 tax return can only be printed and mailed, it cannot be e-filed.
Print, sign, date and mail the tax return to the IRS. Include with the mailed return any forms W-2 and 1099 which have taxes withheld. Go to this IRS website for mailing addresses - https://www.irs.gov/filing/where-to-file-paper-tax-returns-with-or-without-a-payment
There are no penalties for filing a tax return after the due date if filing for a tax refund or there are no taxes owed.
