Sarah, the whole thing sounds fairly traumatic for you.

Are you hoping to do things differently when your next baby comes along?

Posterior babies are known to be longer labours, with lots of back pain.
I'm sure you know that though.
What you describe with Zander's head sounds like caput, where the babies head is squashed so hard against the cervix, the 'ring' sounding like where the cervix was positioned while you were contracting.