it molted a couple of times and I didn't notice the shed skin, or maybe it is still a cat in the leaf ball.

I didn't read about the leaf ball. How much time in between the cat photos and the leaf ball? A 15mm cat is almost certainly only 3rd or 4th instar and shouldn't pupate.

It's possible that it pupated early due to stress, and will not yield an adult. I had this happen more than a few times when I was working with Symmerista. (I've had Anisota do the same thing)

I had it in the house (warm laundry room) feeding it torn oak leaves from outside. I was actually afraid all of the leaves would fall from the trees and I would still have a hungry cat. I guess a shed skin or two could have been somewhere in the huge piles of frass that it made. The small jar would start off mostly filled with leaves and in 2-3 days when I checked back it would be almost all frass with the cat nibbling on one of the last leaf scraps. Dump and refill.

That should've been enough time. If it made it to at least 30-40mm then it was mature and most likely pupated regularly. I would've loved to have seen a final instar photo. Hopefully you'll get an adult from the pupa.

I guess like the "frog in hot water story" it may have changed so slowly I just thought that it looked the same as last time and kept waiting for something to happen. Darn!