DOES MY 2 YEAR OLD HAVE AN ANXIETY DISORDER?

I have a 2 year and 9 month old little girl. She is the 3rd child of our 4 children my husband and I have together. Since she was around 1.5 everyone viewed her as increadibly intelligent, maybe even gifted as she talked in complete sentences, was very intelligent, and excelled in every area over other children her age. About 1 month before she turned to until now, she has begun being what my husband and I would call terrible 2's from hell. We attributed a lot of it to us having our 4th child at this time. However, as time has progressed, her behavior has gotten so bad, it literally dictates a lot of how the family acts and what we do. The normal temper tantrums have now appeared to become laced with anxiety, and they all depend on the mood she is in. Some days are great, others, are hell. Sometimes there are triggers, sometimes nothing appearently sets her off but she goes into hysterics over something yesterday would not have bothered her. The main things that seem to be the problem are when she can't get something exactly right it seems to upset her so much she appears to be physically in pain. For example, if she can not lay a baby doll the exact way she sees in her head to lay it, she is inconsoloble until we are able to figure out how to get it in that position. Also, sometimes noises bother her, or "shapes" she says things aren't the right shape, or she can't hear something when it's very loud, or says something is too loud when there is no noise (she does know the difference). When playing with other children for the most part she does well, however, when it comes to someone playing at our house, the child has to ask permission to come into our home and play. If they don't she gets very upset, and each toy, whether its hers or not, has to be given permission to play with. Please do not say it's a discipline problem, trust me it isn't the issue. We have tried everything and it doesn't work. When she gets upset, there is no consoling her until we can "fix" whatever is bothering her. I thought maybe she had a sensory disorder, but maybe it's anxiety. I don't know. My doctor told me it was normal, but it isn't. Trust me. I am a social worker for the state, I see kids her age every day, in good, bad, and worse situations and she is not normal. So any help would be great. Thanks.