Going from 2 to 3 was easier for me then 1 to 2, I think because I was expecting that shock of "you are such a big kid!" mentality and prepped myself mentally for it, plus my oldest is older and my second is pretty laid back anyway.
Becky, I just wanted to say that if your daughter is anything like my oldest, discipline should wait. Your daughter is in pain, real emotional pain. Her world just got flipped upside down and she's expressing that anyway she can. The last thing she needs is to feel like her mommy is mad at her for hurting. She needs love, lots and lots and LOTS of love, especially in her most unloveable moments.
I know and I hate it SOOO much when I get frustrated with her that I CRY. She NEVER got into trouble before. It hurts so much to see her be this way.