How long have you had Bella? And is she on a fresh food diet? How long has her poop seemed watery?
Birds on a fresh food diet will have droppings that are more watery than those on a pelleted diet. You should still be able to distinguish between the green, white and clear, but it will just tend to be more on the fluidic side.
If, however, you're saying that the droppings are significantly more watery than they usually are, and this has persisted for more than a day... or it has been watery enough that some weight loss has occurred, I would say that you definitely should get Bella to an avian vet as soon as possible.
I have been advised by my vet to remove all fresh food for 3 days. If the watery poop persists, you should see an avian vet. And if the bird seems "depressed" you need to go to the vet IMMEDIATELY as birds only show they are unwell, when they are really sick.
We have had her about about 5 weeks now and she is not depressed and has gained some weight since we got her. She get fresh food daily and very little pellets.