How do I find the right therapist for myself?

In the past I've had a therapist that only ever acknowledged my feelings, and reassured me that what I feel is valid. Overall after a few months I felt as though it was incredibly unproductive. She didn't challenge me or try to dig deeper it was only ever surface level.

Oftentimes we would just sit there in silence, until I would bring up an unrelated subject of no value just to pass time. Why might a therapist only focus on validating feelings instead of helping me dig deeper or make progress?