What metrics proved you had real product-market fit, and how did you pivot?

[Mila92]

I'm a product manager at an early-stage SaaS startup, and while we have a core group of passionate users, our growth has plateaued, making me question if we've truly achieved product-market fit or just found a small niche. We're getting mixed signals from user interviews—some love specific features, but overall retention metrics are mediocre. For other founders or PMs who have navigated this phase, what were the key quantitative and qualitative indicators that convinced you that you had found genuine product-market fit, and how did you pivot your strategy when you realized you were close but not quite there?