Baby not talking - recently changed families - normal?

My 21month old recently went into my parents care (see other posts for full story). The SW recommended a therapist - some where between the SW, the Daycare and my mother they decided she was behind on her speech and that they are concerned because if she doesnt like something someone tells her (if she has to come in before she wants to - or she is told no when she is in a bad mood) she will hit (smack herself in the head - which is new) or bite herself (which is not new) and have recommended she see a therapist. As her mommy I believe what she is doing is a completely normal reaction to the changes in her life situation and that she was/is developing as a normal heathy child. ***I DO BELIEVE THAT A THERAPIST WOULD BE BENEFITIAL*** but I dont think there is anything wrong with her other than a typical pre-toddler learn how to properly express emotions. We can think of 50 words (actually made a list to be sure and everything) that she can easily say (3 or 4 which are actually two or three word phrases) but my mom is right, she doesnt say all of that around them. She understands everything we say to her - listening and understanding are two different things. She has an extremely close and healthy relationship with her older sister and brother. Is kind to animals - gentle with smaller babies She even recognizes her gifted (as in given as a gift - the best way I can describe giving him away) little brother J when we get new pictures of him. Has anyone gone through an adjustment phase similar to hers? I know every baby grows at a different rate but Im judging by what she could do two months ago (time of placement). Is this a normal step backwards because she is away from us or should I be concerned about her developement? I know I set her back by messing up, but was I messing up before they took her away and didnt notice it? I always thought I was doing good but did I miss something?