It Wasn't You. The Bottle Was Already Dead
Most cat probiotics on the shelf are non-spore strains in powder or capsule form. Roughly 93% of those bacteria die in feline stomach acid before they ever reach the gut. So you weren't doing it wrong. You were sold a bottle of dead bacteria — and then sold a more expensive bottle of the same dead bacteria. Spore-forming strains have a natural protective shell that survives the acid and only activates in the small intestine, exactly where her microbiome needs to rebuild.