Please help me resolve my Opperating System (I Think ?) problem

In the future please limit what you post to what is relevant to the problem you are reporting. The rest of the narrative may be interesting but contributes nothing to help us solve your problem.

A Troubleshooting Protocol to Identify Problems or Fix macOS El Capitan or Later

You should try each, one at a time, then test to see if the problem is fixed before going on to the next.

Be sure to backup your files before proceeding if possible.

1. Shutdown the computer, wait 30 seconds, restart the computer.
2. Disconnect all third-party peripherals.
3. Resetting your Mac’s PRAM and NVRAM
4. Reset the System Management Controller (SMC)
5. Start the computer in Safe Mode. Test in safe mode to see if the problem persists, then restart normally.
6. Use Apple Hardware Test to see if there is any hardware malfunction.
7. Repair the disk by booting from the Recovery HD. Immediately after the chime hold down the Command and R keys until the Utility Menu appears. Choose Disk Utility and click on the Continue button. Select the indented (usually, Macintosh HD) volume entry from the side list. Click on the First Aid button in the toolbar. Wait for the Done button to appear. Quit Disk Utility and return to the Utility Menu. Restart the computer from the Apple Menu.
8. Repair permissions on the Home folder: Resolve issues caused by changing the permissions of items in your home folder.
9. Create a New User Account Open Users & Groups preferences. Click on the lock icon and enter your Admin password when prompted. On the left under Current User click on the Add [+] button under Login Options. Setup a new Admin user account. Upon completion log out of your current account then log into the new account. If your problems cease, then consider switching to the new account and transferring your files to it - Transferring files from one User Account to another.
10. Download and install the OS X El Capitan 10.11.6 Combo Update or 10.12.6 Combo Update or Download macOS High Sierra 10.13.3 Combo Update as needed.
11. Reinstall OS X by booting from the Recovery HD using the Command and R keys. When the Utility Menu appears select Reinstall OS X then click on the Continue button.
12. Erase and Install OS X Restart the computer. Immediately after the chime hold down the Command and R keys until the Apple logo appears. When the Utility Menu appears:

1. Select Disk Utility from the Utility Menu and click on Continue button.
2. When Disk Utility loads select the drive (out-dented entry) from the Device list.
3. Click on the Erase icon in Disk Utility's toolbar. A panel will drop down.
4. Set the Format type to APFS (for SSDs only) or Mac OS Extended (Journaled.)
5. Click on the Apply button, then wait for the Done button to activate and click on it.
6. Quit Disk Utility and return to the Utility Menu.
7. Select Reinstall OS X and click on the Continue button.

If none of the above helps then make an appointment at the Apple Genius Bar for service. If you need to find an Apple Store - Find a Store - Apple.

That is indeed a sad story because the initial symptoms presaged the eventual outcome: that your hard disk was already operating in a state of failure, and that it requires replacement. Apple could have performed that repair for about the same amount of money which would have included a warranty.

Your precious photos that now reside on the external disk are probably ok, but you won’t know for certain until that Mac is properly repaired. Contact Apple to determine your options. Use the link above right, and stay away from so-called “Mac guys”.

The initial mac guy was wrong and charged you too much. And it has gone downhill from there. You need to make very clear to who ever repairs the mac that you do not want the internal drive erased. Replace and return to you unchanged.

I spent over a week on the phone with multiple different MacSupport agents 5 or 6 who tried

Where did you hear about these people? It's best to consult with people here first.

You need to employ a backup strategy. You need to get another external drive an turn on Time Machine.

This is controversial around these parts, but I recommend you get your photos out of the Apple ecosystem and store them as one photo per file on multiple external storage devices. One device should be off site. Using a cloud service is fine. Remember a lot of cloud services are sync services. That is should the file be deleted on the local device, the photo will be deleted in the cloud. For this reason, I never install the cloud service software on my computer. I use only file upload. For those who complain, my assessment is that the apple Eco-system doesn't match Library of Congress's requirements for digital archiving.

informative video:
http://www.digitalpreservation.gov/multimedia/videos/personalarchiving-photos.ht ml

printed version
http://www.digitalpreservation.gov/personalarchiving/photos.html

General information on digital preservation:
http://www.digitalpreservation.gov/personalarchiving/

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