How do I stop 'script-switching' anxiety before talking to my grandmother?

I grew up hearing bits of Western Armenian at home, so I can read the alphabet, but my brain completely freezes when it’s time to actually construct a sentence. I’m tired of using generic apps that don't help with conversation. I’ve started using Chickytutor.com to practice specific 'family talk' scenarios so I can finally have a real conversation with my grandmother without switching to English halfway through.