Why is my mac sending messages from my email instead of my phone number. It was sending messages from my number when i first got it but now its not :(

I have had this issue as well when I've had to log back into Messages after an AppleID authentication issue. macOS is stupid and modifies the preferences of the Messages app when this happens. Launch Mesages on the Mac and select "File --> Preferences" where you should see your email address listed. Uncheck the box next to your email address and your messages should now be sent using your phone number.

Hello stormy_,

Welcome to Apple Support Communities!

If we understand your post correctly, your getting messages on your Mac from your email address instead of your phone number like it used to before. We're happy to help!

Try the steps provided in this article for help adding your phone number to Messages: Add or remove your phone number in Messages or FaceTime

You may also want to check your Messages preferences: Change iMessage preferences in Messages on Mac

Let us know if you have any questions.

Thank you for using Apple Support Communities.

Take care!