Well she fell asleep at about 11am, which I wasn't impressed with. I found a local vet and they told me to go straight in, I guess they had a quiet day, it didn't seem to be an issue.
The vet was incredible. He took a full history and spent about an hour discussing her origin, care, setup and behaviour before even uncovering the box to examine her. From all the worries I shared, he was surprised that she was so big and so healthy-looking!
Upshot is that she has a hookworm infestation, which is pretty much negating most of the care I'm giving her, though he says that she would be long dead if I hadn't been following the advice I've been given here.
He says she is slightly dehydrated and her tail is skinny, but she is strong and alert, more so than he was expecting. She's had treatment for the hookworm, and I'm to take her back in 2 weeks for a follow up, and he said to call any time if I have any concerns or questions. He also weighed her (66 grams) and said that she isn't gravid, and is probably too underweight to start producing eggs yet.
Such a relief! $175 very well spent! He also said to get rid of the substrate, as that will be helping the hookworms, and just to get more live foliage.
So anyone needs an awesome herp vet in NY, go see Dr Raiti at the Beverlie Animal Hospital in Mount Vernon! He also breeds snakes and takes in lots of wildlife rescues including one 'box turtle' which a woman found being used as a football by some children, and turned out to be a Russian tortoise, which he repaired and treated and adopted.
And someone gave him a baby ball python which they didn't want any more, and he's offered it to me! Woah... my menagerie grows... It's still recuperating and only taking live food at the moment, which I really can't manage, so he's going to get it healthier and onto thawed pinkies and give me a call.