It sounds like she has had a parasitic infection for a long time, probably due to the dirty conditions in her prior home. They won't typically go away on their own once they get into high counts/loads, and they require a fecal test to determine what the parasite is and what the count is. Most reptile vets won't treat a Coccidia or a Pinworm infection unless the count is high (not low or moderate), but if she's had runny stools for that long then she probably has an infestation, based on how you described her prior living conditions. There are also other parasites that can hurt them in low counts.
You need to find either an experienced reptile specialist vet or a Certified Reptile Vet and make an appointment ASAP. You'll need to take a fresh stool sample with you to the appointment, otherwise they won't be able to run the fecal tests. If it's all runny then wait for her to go in her tank/enclosure and then scoop as much up as you can into a little baggy, they can test it. She most likely needs at least one or more prescription meds and a probiotic, which I would start her on now even before getting her to a vet. Has she been losing any weight? That's what you have to watch, if you let parasites go for too long, specifically any type of worms, they will eat all of the nutrition she eats (basically they steal her food from her) and then they start losing weight.
Also, if she's 9 months old, she should still be eating a large amount of live staple insects every single day, at least two live feeding sessions a day where she gets to eat all she wants. They do most all of their growing during their first year of life, so it's very important that most all of their diet is live insects (no mealworms) up until they are a year old. What is her daily diet?