I found a bolt under my seat, so that is most likely the problem the bolt fell out!

Thank you for your write up, is there any way we can get larger pictures its hard to see

 

My pleasure Snook. This site has already helped me quite a bit,
I'm happy to give back.
I've been thinking about it and I really think that you should try
moving the seat forward to get access to the swivel bracket,
flip the seatback forward and have someone pull on it so it lifts
the seat upward while you swing the bracket up and insert the bolt.
The bracket might be snug as its been sat on for a while.
I stuck a phillips screwdriver into the bracket bolt hole to break it loose -
it gave just a little resistance.

As a frame of reference, pic 13 is a side view, and pic 18 is shot as if there were no floor and you were looking up past the black floor rail at the bolt from outside the car. A mirror and a flashlight might help.
If you can't get it that way, the disassemble isnt really hard at all.
Just that damn C ring. Thankfully it comes off downward and not upward.
If anyone has a slick way to get that off I'd love to know what I missed.

Clearly I didnt try this method so I dont know if it will work - its worth a shot though.

Last, I think its a good idea to re-torque the right rear bolt on the opposing bracket. If one fell out, why not both eventually? Thread lock makes sense here too.