To be honest, I am not sure she could be trusted at other peoples homes with carpet.
Mine are 3 yo - they are pee pad trained. I have liter boxes that I put the pee pad inside of. This way they have to step into the box to use it and not mistake it for the carpet. We only have throw rugs and they have all been marked from when they were babies, so I don't worry about them peeing on them anymore. Roxy still does have marking habits though. She has to mark the 'smaller throw rugs' after they have been washed. I am not sure that I can break her of this habit. Also, after 3 yo - mine are still UNTRUSTABLE in other peoples homes. Not that they would have a full fledged pee - but with Roxy and her marking, she sure would have no problems doing that. If I put pee pads down they will use them at other ppls houses.
The problem you have may be that she isn't really potty trained fully outside and she really isn't potty trained fully inside. She really may be confused
