I've been diagnosed with an autism spectrum disorder, and like you, my brain just sort of gives me the concept of a word instead of making the actual literal sound of a word when I include the word in my internal monologue. For example, when I think the word "Apple," my head doesn't silently whisper "apple" in an internal voice. Instead, my brain just sort of bundles up an image of a shiny red fruit, the taste of biting into an apple, the shape my mouth makes when speaking the word, the texture of a crisp apple slice, and a visual image of the word "apple" printed in black and white, times New Roman font into a single thought and throws it at me in a compressed little concept. Usually, my internal monologue is just a combination of images of text and my personal encounters with nouns and verbs. It can be a little overwhelming at times, especially when I'm trying to turn a complicated thought into a spoken sentence. However, the whole conceptualization thing is generally quick enough that it slows me down to try and actually hear what my brain is thinking as a spoken sound.