Did you efile or mail it? If you efiled was it Accepted? 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 and spam/junk folder.
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?
If you efiled there should be an Electronic Postmark page. Probably near the end. That is your proof and signature.