No i don't have anyone to compare either of them to. They don't go to child care anymore which is a pity.

Also, what do they do in the consultations? Because if they want her to talk to them well she won't as she never talks to strangers (good thing i supose!) she jsut shys away. So they might think she cant talk at all.
I am a speechie. It doesn't matter if she doesn't speak in the session. The speech path will ask you lots of questions about her communication to get a good idea of how she's going. They can also do non-verbal tests (which most children, even shy ones, usually co-operate with) to assess their ability to understand language, which is an area you expressed concern about. The longer you wait to get her seen the worse the delay could become, given you mentioned that you think she is going backwards. It won't hurt to have her seen, even if she has absolutely no delay so I can't understand your families arguement there TBH. Your description of her speech sounds typical of a child younger than 3 years.

As far as Charlie is concerned, does he repeat sounds/words that he hears you say, other than the ones you mentioned? He should have about 5+ words at his age. An interest in communication, even if he is unable to use many words, is what your looking for at his age.

Has their hearing been checked?