Why does my -miş suffix usage sound so awkward to my Turkish relatives?

I grew up hearing Turkish at home, but I never studied the grammar formally. Whenever I try to tell a story about something I only heard about from a third party, my aunt says my use of the evidential past sounds 'robotic' or 'wrong,' even when I follow the textbook rules. How can I better integrate the evidential past to sound more natural rather than like a grammar book?