Welcome to the forum Ginger
I've only been dancing for 2.5 years, but maybe I can still give some advice.
As for the hip shimmy, I can't really tell because I don't know which shimmy your teacher was doing. Hip shimmies usually get easier when you bend your knees a little more. For shimmies I can walk with, I'm not sure if use only my knees to create them
.
As for the shoulder shimmy, wat helped me was practicing them by sitting down, so you can't move your lower body. Then slowly move your shoulders alternating forward and back. If you imagine you have a pencil in between your breasts (my teacher's words, not mine!), try drawing a horizontal line with that pencil.
If this works, you can try do speed up the movement. Once you're more comfortable with that, try it while standing still, than while walking slowly etc.
Good luck!