Hello there, helell.
The following Knowledge Base article provides some great information in regards to AirPlay Mirroring and not seeing the mirroring icon:
About AirPlay Mirroring in OS X
http://support.apple.com/kb/ht5404
If you don't see mirroring options
If your Mac and Apple TV are on the same network, but no AirPlay Mirroring menu appears, your Apple TV may be asleep. Simply press a button on your Apple TV remote to wake it up. After a few seconds, the AirPlay Mirroring menu extra appears. If you still don't see the options you expect, make sure your Apple TV has the currentsoftware update installed. Also make sure that you have the "Show mirroring options in the menu bar when available" option selected in the Displays pane of System Preferences.
There is some additional information to review in this article as well:
iTunes: Troubleshooting AirPlay and AirPlay Mirroring
http://support.apple.com/kb/TS5209
Thanks for reaching out to Apple Support Communities.
Cheers,
Pedro.