Have you read Steven Pinker?

He wrote a book about language. He said thinking and talking are 2 different cognitive functions.

Here’s a clear quote from Steven Pinker that highlights the difference between thinking and speaking:

“Knowing a language, then, is knowing how to translate mentalese into strings of words and vice versa. People without a language would still have mentalese, and babies and many nonhuman animals presumably have simpler dialects.” — The Language Instinc