R.M.
This has become a battle of wills..is that how you want to live your life and is it the kind of message you want to send to your daughter? She is becoming old enough to start feeling a little independence from you and a sense of "entitlement"...dont' stifle that!!! How would you deal with an adult who didn't want to go to the bathroom?? Would you force him to go and sit in the bathroom anyway? ASK her if she needs to go potty....discuss how much nicer it is to have a dry bottom and how easy it is to go in and sit on the potty. Try reading a book to her while she is in the bathroom...or have her tell you a story ( great for expanding her imagination and vocal skills)...sing songs together while she is in there. Make it enjoyable.
What does time out teach a child? Do you TRULY think that a three year old is sitting in that bedroom, all alone, thinking "wow, I really disappointed Mom and Dad when I refused to pick up my toys, but I am going to do better next time". No...she is upset and angry...and probably wondering why you shoved her off by herself when she has all of these emotions that she doesn't know how to deal with boiling up inside of her!! Try going to her instead of asking her to come to you...give her choices...empower her...teach her about decision making(which shirt would you like to wear with your shorts...the red or the blue?) teach her about respecting others by showing her respect ( "Honey I know you are really enjoying playing with your toys but remember that in about 10 minutes we need to think about taking a bath")....and most of all make sure she knows that you love her and value her as a person...and that you are taking your job seriously...to be her support system...to always be there for her and to help teach her how to be the very best person she can possibly be!!