Engorged is that feeling of your breasts being super-full, hard, lumpy...
The fact that you feel better after your baby nurses suggests that he's getting the milk out, even with the shield and augmentation.
Were your nipples completely severed and reattached, or only lifted up in order to place the implants? It's the former type of surgery that tends to be most problematic for breastfeeding.
You wrote that you are worried about brain damage- I assume you're worried about jaundice? Is your baby jaundiced at this point, and if so, is he a sleepy nurser or is he nursing at least 10-12 times a day?