You've done a WONDERFUL job!
As I was reading your story it reminded me of Malibu, and especially Pretty. Mallie took me 5mo to first-touch from time of TNR. Pretty took 14mo to first-touch.
Mallie did very well when I would let her in the house with our other cats. My cats are curious and I like to do cracked-door-nose-sniffs and when the hissing was almost non-existent, I'd open the door wider for some footsie and eye-to-eye contact. From there it was a short step to letting Mallie come inside.
Pretty, on the other hand, took a *very* long time. She was *very* freaked out coming in the house. She'd come in at first for only a few minutes and then want out immediately. That progressed slowly, but for the first few months, the TV *freaked* her out. She just couldn't understand that the motion on the wall wouldn't be able to touch her. As she began to spend more and more time inside, investigating, playing and even napping ... when I saw her use the LitterChest, I let her stay in overnight. She eventually spent more time inside than out, and when two aggressive tomcats moved into the area, she finally became a permanant indoor resident.
Overall, I'd say she took about 2.5yrs of socialization outside before she came inside and then another 1.5yrs outside/inside, slowly transitioning to more time inside than out and finally becoming completely comfortable and confident as she became a full-time indoor kitty.
I think you've done a great job with your Shadow!
Here is Pretty, she has a tipped ear, too.
Still new to being indoors, notice her upright posture and wide pupils even though I made sure to stay low to the floor to take the pic:
Now notice how she is reclining with feet curled under her or to the side, and relaxed eyes even though I am 'looming' over her while she is on the floor: