extreme shyness and other issues

I have some questions about my daughter's social development.  I've been reading things online but am not really getting anywhere.  
My 3 year old (4 next week) is extremely shy.  If we go to a park or playground where there are other children, she will not play.  As soon as they leave, however, she will play.  She is not shy around me, her dad or brothers and sister, and certain other close family members.  Anyone else, though, she will not talk to.  I just have to explain to people that she is very shy, because I'm afraid they think something is wrong with her.  This past week, on Thanksgiving, we spent the evening with my dad's family.  It is a big, noisy family, and there were other young children there.  She would not play at all, and insisted on staying right by my side the whole time.  She is very clingy, particularly with me.  I'm a stay at home mom so she is with me most of the time.  
At home she is far from shy.  She is affectionate and speaks a lot.  I'm not really concerned about Autism because of these reasons.  She has no problem making eye contact with people she is comfortable with.  She does have a few of the Autism symptoms, such as sensitivity to noises (she is petrified of public toilets) and lining things up.  When we go to my in-laws', she goes immediately to the toy cars and lines them from the bedroom to the dining room. She will not play with them, and gets upset if someone messes them up.  We also have some behavioral problems, although they are minor.  When she gets upset about something, it's not uncommon for her to kick, stomp or throw things.  We also are having a terrible time potty training her.  She'll do good for a day or two, then want nothing to do with it.
She had some developmental delays when she was born and received OT and PT until she was about 18 months old.  She also was fed through a feeding tube until around that time because of aspiration.  She had a seizure when she was a day old, but numerous tests were ran and nothing significant was found to have caused it.  
She is a very intelligent child.  She is already learning Spanish by watching Dora!  She has some issues with her speech that we are going to talk to her doctor about.  She does not enunciate her words well.
I know this is a lot, and I'm sorry if it seemed like I was rambling and it was in no particular order.  
I guess I just wanted to get some advice or feedback from others who may have gone through the same thing(s).
Thanks.

[jdtm]

I belong to a support group for parents and teachers of children suffering from anxiety.  Many of the children in the group suffer from Selective Mutism which is a severe anxiety disorder in which the child is unable to speak in "perceived" unsafe environments.  I suspect your daughter is "selectively mute".  The difference between "shy" and "severe anxiety" is function. - a shy child can speak, eat, use the washroom, interact, etc. in all environments while a child suffering from severe anxiety can not (the severe anxiety appears to paralyze the brain so the child is unable to function).  From your description, your daughter fits into the "severe anxiety" category.

Your words - will not play, not shy around me ...close family members, will not talk to, very clingy, sensitivity to noise, petrified of public toilets, gets upset, not uncommon for her to kick stomp or throw things, a terrible time potty training, a very intelligent child - these behaviours are very common to children suffering from anxiety or, as I suspect in your case, selective mutism.  It is also common for children who suffer from selective mutism to have problems with expressive and/or receptive issues.

The best site on the internet re this topic is "selectivemutism.org" and I urge you to check it out.  Pay particular attention to the FAQ's as well as the downloads and articles as well as the message fourm.  Treatment involves intervention, therapy and possibly medication but the prognosis is excellent if the child receives treatment early.  Please write back  with any questions that you think I might be able to help.

[crazyhoosiermama]

Thank you so much!
I was actually reading about this earlier and a lot of the traits fit.
I will definitely check out the web site you suggested.
Thanks again!