Your Time Machine backup is too small, and therefore, Time Machine is not backing up. Get a new and larger drive. I recommend using a SanDisk Professional G-DRIVE - Western Digital as your backup drive. You can then follow the Apple Support steps to setup your Time Machine backup: Back up your Mac with Time Machine - Apple Support.
I personally also use iCloud in addition to Time Machine to sync all my files and photos to all my Apple devices. Although iCloud is not a "true" backup service, iCloud can also act as an emergency backup, but this is why iCloud should be used in addition to Time Machine. I strongly recommend using it.Here are some resources on setting up iCloud for Mac:
You have adware. Remove it with Malwarebytes for Mac.
Your Security and Updates are disabled. Please go to System Preferences > Software Update, and turn on the following:
- Check for Updates
- Download new updates when available
- Install App Updates from the App Store
- Install System data files and security updates
Then, go to System Preferences > Security & Privacy > General, and make sure the "Allow Apps downloaded from" is set to either "App Store" or "App Store and Identified Developers" (that may be the only options shown).
Delete Adobe Flash. [Instructions] It is no longer used.
You have lots of Internet Plug-Ins. Go through and delete them in ~/Library/Internet Plug-Ins/ and /Library/Internet Plug-Ins/.
Next, Start up your Mac in safe mode - Apple Support, login and restart into normal mode. Then, run First Aid on your Fusion Drive: How to repair a Mac disk with Disk Utility - Apple Support.
Finally, use DriveDx to check the health of your Fusion Drive and upload the two reports.
Cheers,
Jack