Hi Jonathon003,
My orthodontist also didn't mention my jaw at any time when I had braces the first time round. It was only when I went back to him a few years later because I wasn't happy that he said he'd known I would need surgery to fix things completely. I was a bit annoyed about that as well, but I think he was hesitant to point out the problems to a young teen who probably hadn't noticed them yet. Plus, I assume I needed to stop growing first.
From your photos I can't really see much of a slant in your bottom teeth, probably because mine was worse! Both my top and bottom teeth were slanted slightly outwards. As far as I know, your retainer didn't cause this, it's just the way they grew, possibly because your mouth is small... I had to have a few teeth removed and braces to pull the slant in.
As for your chin, I have often wished I was male so I could grow a beard to hide mine

Yours looks kind of similar to mine, and mine is basically because my lower jaw didn't grow far forward enough. I'm don't know exactly why your lower lip jets out like that (mine does the same), but I sometimes wonder if it's because the bottom jaw and chin hasn't grown far enough forward to actually fill it out enough and give it shape... If that makes sense.
Obviously, I'm far from being an expert and this is just conjecture. Your orthodontist is really the best person to speak to!