Got results back from the hospital. They said the culture did not grow any bacteria, so she does not have a UTI. Basically they think it's behavioral or she could have had something called feline sterile cystitis. They said to try maybe getting her a lower, easier-to-get-into litter box and use Feliway. As far as her bloodwork at the primary vet, which had revealed slightly elevated kidney levels, they said that could be due to early renal disease but they feel it's more likely from a pre-renal cause like dehydration and inflammation. They said it's something to keep an eye on and that if she experiences symptoms similar to pancreatitis again, to have her re-evaluated because sometimes kidney disease can disguise as a digestive issue. But overall they don't think it's kidney-related.
So all-in-all it sounds like this was all behavioral?

I don't know why; she's an only child, so there are no other cats around to irritate her, and she has plenty of toys and cat trees and hide-aways. I'd say she could use more play-time, but when I try to play with her she acts like I'm being a pest, lol. I'll see if I can find a better box for her (she already has two!) and try to get her more active and engaged.