I would be concerned now by soft stool, how old is she? Have you noticed any normal formed fecal poops? My bun experienced intermittent soft stool and will occasionally have it if I try offering a new food into his diet. What is she currently eating and what was her diet previously?
If it was my rabbit I would find a rabbit savvy veterinarian and get her in for a fecal float for bacteria/parasites and a wellness check before her syptoms progress. You could also use that time to consult with your veterinarian about basic husbandry for your new rabbit.
Welcome to the forum