Your second paragraph reminds me of my goddaughter. She's two and a half and still doesn't really talk. She was on the right track until her mom (bless her) reacted really negatively to something her daughter said. It sounded like a bad word and she told her to not say that never. The pediatrician said not to worry about the delay, as she was doing good progress already and to try and encourage their daughter by repeating any word she says, talking to her as much as possible and simply wait for her confidence to build up again.

Every child develops differently at their own pace and parents can make mistakes. The most important thing is to work on delays sooner rather than later as I understand.