How do I confirm my 2018 taxes were filed?

Just paying the Turbo Tax fees does not file the return.  You had to continue on through the File tab through the 3 steps and hit the big orange Transmit Returns Now button.  Maybe you didn't finish filing it or it Rejected.  When you log into your account you should also see the status and if it was Accepted or Rejected, Started, Printed, Ready to Mail, etc.  what does it say?

Then when you efile you get back 2 emails.  The first email only confirms the transmission.  The second email says if the IRS (or state) Accepted or Rejected your efile. Check back though your emails if you have them.

What does it say in your TurboTax account?  Does it say the return was "Accepted," "Rejected," "Ready to Mail" or "Printed?"  If it says anything other than Accepted, it was not filed at all unless you put it in an envelope and took it to a mailbox.  If the e-file was rejected and you did not notice and follow up to fix it. it was not filed.  Or if you chose to mail it but did not mail it yourself, it was not mailed----TurboTax does not mail it for you.

You have an order number---but paying your fees does not file the return.  If you did not go all the way through the FILE section and click a big orange button that says "Transmit my returns now" the return was not filed.

You can still print it and mail it now ---click on Add a State to let you back in and then print it, sign it and mail it.

When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s.  Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS/state received the return.

If you are getting a refund, there is not a penalty for filing past the deadline.  If you owe taxes, the interest/penalties will be calculated by the IRS based on how much you owe and when they receive your return and payment. The IRS will bill you for this; it will not be calculated by TurboTax.