How do you think quickly if you need to say everything in your mind? Is the voice very quick?

Pretty quick, yeah. It's basically my voice, but also, I don't need to breathe or move my mouth or anything. Ever heard the term "stream of consciousness"? Also, grammar and punctuation aren't necessary, I can just talktalktalktalktalk and I understand myself because I always know what I'm saying.

I'm sure if you could listen to my thoughts it would sound like a fucking mess tho lol

But also, there's a difference between when I'm just thinking about stuff to myself and when I'm busy doing something. If I'm in a flow state or "in the zone", I don't necessarily monologue everything I'm doing. I just do it, y'know? It's only when I slow down to think that my thoughts actually become dialogue again.

It’s also unfathomable to me how people can think of what they need to do tomorrow and not see it.

I can't imagine why you need to see it! I know I need to lay some mulch on my garden tomorrow, I don't need to visualize that? I can just make a mental note of it and keep that thought stored away as part of a to-do list. What would I even use pictures for when I can just tell myself "I need to do X, Y, and Z"?

I just think we don’t understand our own internal processes very well. The conscious part may come long after we had the thought and if you say it or see it doesn’t matter.

Well yeah, consciousness is an illusion. I think they've demonstrated with active brain scans that our conscious thoughts come after we've already made subconscious decisions. We make up our minds before we know it, consciousness is more like a way we convince ourselves to do the things we've already decided we want to do.