Please don't take away something so important that she's wanted for so very long as her "punishment" for not being what you want her be so quickly. It's only been a week -- did she learn to walk perfectly that quickly? Just help her understand and accept this big physical change with very different physical dynamics.
Pooping is so much harder than peeing -- be sure she has something to put her feet on for balance and pressure, and perhaps some books/music/woobie she can choose for the time before bed when she typically goes to "get in the mood." Some kids also get scared they are losing "part of themselves" when they poo, and then see it get flushed away. I feel that one tip to make the child "clean themselves up" is so demoralizing!
And think how hard it is for us adults when we have to poop in the public restroom with an audience???
Kids have accidents so get a good mattress cover and accept you'll use it for the next 2 years, and don't worry so much because no one's perfect, not little or big people. And be happy she doesn't poop in the corner or spread it all over the walls like mine:)