Hello HDOwl,
Welcome to Apple Support Communities!
We understand your iMessages aren't syncing between your devices and Mac. We'll be glad to assist.
Let's start off with checking some settings on your devices. On your iPhone, go to Settings > Messages > Send & Receive. On your Mac, open Messages and choose Messages > Preferences > iMessage. Verify both devices are signed in with the same Apple ID. You can then turn on Text Message Forwarding. This will ensure your text messages are sent to your Mac. Go to Settings > Messages > Text Message Forwarding. You can learn how to set this up here: How to forward SMS/MMS text messages from your iPhone to your iPad, iPod touch or Mac - Apple Support
If you send a message from the Messages app on your Mac, does that appear on your iPhone? If not, please follow this: If you can’t send or receive messages on your Mac - Apple Support
You can also Access your messages on all your Apple devices if you Use Messages in iCloud. This won't back up your messages conversations to iCloud, but will keep them up to date between all your devices signed in with the same Apple ID.
Take care.