When Amber wakes up from being tranquilized, her stomach is completely flat. After childbirth, it takes at least a few weeks for a woman's stomach to get close to how it was before.
Taylor is deemed "mentally unstable" because she has chosen to give up her baby after delivery. This is absolutely not a symptom of being mentally unstable. If a woman decides she can't raise the baby, it's not uncommon for her to give it up immediately after it's born.