My Devanagari reading speed is okay, but my brain freezes when I try to reply

I’m a false beginner; I can read signs and menus written in Devanagari fine, but as soon as a cashier talks to me, my brain turns off. I think I’m too focused on translating the script in my head rather than listening to the sentence flow. Should I stop reading for a while and just focus on audio, or is there a way to bridge the gap between script recognition and listening confidence? I am asking specifically about learning Nepali, not a generic study routine.