I am in a very similar situation to you right now, so I have no help, but I feel your pain. I have 3 kids transitioning right now. Just turned one year old twin boys (who are fine and never had a problem transitioning) and an eleven month old girl who is full time. I am currently in week 3 with her and she does the same thing as your little one. As soon as I put her in the highchair she would cry and scream and wouldn't eat. She wanted me to hold her so she could eat. No way that was happening! I just kept reassuring her and telling her she was fine and eventually she stopped crying for the most part. If I leave her sight she cries and screams and again I tell her to stop and that she's fine.
I know she is babied at home, her mom tells me she screams if mom leaves the room too.
I had a day from hell yesterday because she cried pretty much all day and set all the other kids off too and it is getting to me too. My two year old daughter tells me she doesn't want her here.
When the kids are playing she is constantly trying to crawl in my lap and cries if I tell her no. I put her down and give her a toy and tell her she's okay, but that only works sometimes. The only thing I have found so far to stop the crying for the most part is to allow her to have her blankie with her at all times. She normally will just cuddle with it and stop crying, then rejoin in the playing or just sit there and watch the kids play.
I too hope this ends soon.