There's not a thing wrong with your grip. Honestly, your squat isn't nearly as fucked up as you think either. Make your stance a touch wider. Lose the foam roller. Drive your knees out a little more and point your chest at the ground. Stop worrying about emulating the pictures in the book, too. Everyone looks a little different in the squat based on their segment lengths. Keep your chin down on the ascent. Everything is going to be okay. I promise.