Hello Humbug and welcome
It's unfortunate that you need to sell so soon after buying
One can get used to the weight and learn how to handle them to make it easier; though having already strained your back, perhaps a luxury doll isn't for you.
However if you
do sell your doll, but still want to have a doll at all, please ask the forum for advice on the less weighty girls; plushies, Kimbers, and so on.