Dying HDD, trouble updating a Windows 10 backup, maybe some other things

[computerpccomputer]

Hope this isn't too hard to follow or long.

I'm not sure where this goes; it deals with Windows 10, firmware, and hardware. I hope I didn't miss something when making this thread, but I'm feeling a bit rushed...
Keep in mind there's a lot I don't remember from when I started to trying to back up my HDD. I don't know if I directly copied the files, I don't know if I used Windows backup, I just don't remember at all what I did and its really, REALLY frustrating.

Also, yes; I was negligent.

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Over a year ago, I was told my primary HDD is showing signs of dying, so I got an SDD, a new HDD, did a full backup, and set up automatic backups. But I never found time (or courage) to update my hardware. I realize I *should* update before my drive crashes, but I never did.
Then, I don't remember the details, but it stopped backing up and I stopped using it. When I checked today, I noticed the automatic updates were still on and referenced the SSD, so I dunno if that can be an issue...

Flash forward to present. I'm finally troubleshooting the issues with my SSD because I'm getting some deathly concerning slowdowns and random issues. When I go to backup settings it says:

Size of backup: 0 bytes
Total Space on Seagate Backup Plus Drive (D:): 1.81 TB
Last backup 8/8/2018

If I hit "back up now", it says "Backing up your data" with a loading circle, but nothing happens; a minute or two passes and the screen just returns to saying 0 bytes, last update 2018 etc. and correctly references drive D as the SSD.

I wanted to check if the SSD backup was corrupt or something and thought a quick way to do that would be to casually click around and see what's actually stored on it.
Looking around the SSD, I found out that I need to click a permission thing to get access to a folder labelled 'WindowsImageBackup' on my external. I did access it. I assume this is because its a backup (though I am curious about this too).
There's a Backup folder with hard disk files... Size looks right for a full backup. I guess this means my SSD works at least?
What is going on?

So basically:
1) How do I know my stuff is actually backed up properly?
2) How do I... do whatever I need to do in order to get have a current full backup that I can then use to migrate my full system? What is going on? Please god make it stop so I can concentrate on my calc 2 finals and IRS papers

...I think the rest is for Google. I'm frustrated, but I have to do this because I'm almost certain my drive is failing.

[Lisa_maree]

Hi

OK first off lets check the health of your hard drives with a program called HDsentinel from here  https://www.hdsentinel.com/download.php

If you post a screen capture of the front screen of HDsentinel with the Seagate Backup plus plugged in we can see both the health of the drives and how much space is used.

The Seagate backup plus has software supplied called toolkit for doing backups either a full copy of the drives in the computer or just some folders.

A description of how  to use Toolkit is available here https://www.seagate.com/au/en/support/external-hard-drives/desktop-hard-drives/backup-plus-desk/

If the backup was created with windows backup then the folder and files created are just like another drive on your computer and you can view it's contents and copy files from the backup set.

[Geek-9pm]

From dictation.

The advice given to you by Lisa_maree is very good. What I have to say here is not intended as a contradiction. It is impossible alternative solution to your problem.
I think you should get another computer. Preferably one that has some type of guarantee or support available for it. If price is a problem you could buy a refurbished PC that will give good performance for most common operations.   
It is not clear what you need in a computer. Do you play a lot of games? Do you need it for some kind of development that requires extra speed and productivity?
For just general browsing and social media you don't need very much computing power. There are some refurbished computers available on eBay that come with a warranty and sell for less than $150. Of course, you have to supply your own monitor. Keeping your old monitor can save you quite a bit of money on a refurbished PC. Most of the time the problem is not with the monitor anyway, it is usually with the computer itself.
That's all I have to say. This is with sincerity and frankness. I have had computers for many years and find  that sometimes the best thing to do is just get another computer and throw the old runaway. I used to be able to fix things myself, but I have lost that ability and I am getting to be very forgetful. So I better post this before I forget how to do it.

No, I am not joking. I really am going downhill.   
End dictation.