K.S.
I recently went throught the same thing with my 3 yr old daughter while I was pregnant with our 2nd child. We had done some of the same things, let the child sleep with us hopeing that it was just a stage she was going through. However, 3 weeks later she was still sleeping with us and throwing awful fits with us. She had slept in her bed since she was a baby never sleeping with us. We couldn't figure out how to get her back into her bed, then our peditrician gave us some advice, i love my peditrician. He told us to not let her sleep with us, to make a pallet beside our bed and make her sleep there. He said that she would eventually decide to go back to her bed. It took about a month of her sleeping on the pallet in the floor to move back to her bed. She was 2 when she went through all this and I was pregnant. I think a lot had to do with the 2nd child and her not knowing what it meant and not understanding why mommy couldn't carry her around anymore.
I hope that this information helps you like it did me.