That's fair! We all have those things we worry about.Probably will need time.
Vet okayed giving this supplement with L-tryptophan in it, says it's worth a try, though it will take time as well.
I don't think she's struggling to pee in any way, she uses the litter box just fine, no hesitation. There's also no straining when she's peeing on the bed, as far as I can tell from the video. And there was nothing in her tests to show a problem, vet thinks it is just stress. I worry about giving cranberry stuff or anything that increases the urine ph because it puts extra strain on the kidneys. My cat with kidney disease died earlier this year, so I'm extra paranoid about this stuff.
Could be FIC then, just stress related bladder inflammation causing her to pee elsewhere. Extra water and giving food through enrichment is very helpful with that.