Welcome Tayzer,
I'm also starting my DMT journey so I can't comment on how DMT affects your dreams, I can only comment on how shrooms affected mine.
The first thing I would say is the answer to your question is generally understanding the question itself. You asked how could your mind have it's own mind? But are you so convinced that you yourself have a mind? Where is this mind? Where does your minds mind exist? Can you point to them?
I think it was Alan Watts who said (paraphrasing) there was a student who came to a Guru, saying his mind was torturing him and it wouldn't stop being negative. So the Guru asked the student to show him his mind so that he could help him fix it. The student could not produce his mind, and thus his problem was solved.
You're asking many questions but you already have some answers. For me Journeying only made the distinctions between Dreams and Reality more and more indistinct. As I investigated my dreams further I came up with things like in reality there is physical feelings, and smells and taste, only to have my dreams begin having the same perceptions. In essence my dreams became more and more real, and reality became more and more dreamlike. Simply put the more you try and put the distinction between them in stone, the more the stone will begin to crumble.
Now reality is a recurring dream I have, and my dreams are journeys into infinity that I purposely label as unreal so as to not give them the power to affect "waking" life. My dreams inspire me to create in this world. Reality is structured and coherent, when dreaming I have no need for the structure and can thus go over the top and really shake things up. Once things have been shaken up I can decide what is worth introducing to my structured reality.
In essence, both became dreams to me. One structured, my permanent and ever growing creation. One unstructured, my permanent and ever changing inspiration.
But that is alas my path, and I hope it has shed insight for you on yours and if not then I hope you find the answers you seek.
Safe travels,
No One.
Take everything said with a grain of salt, every rubix cube is different and what works for "me" may not work for "you". <3
βA man goes to knowledge as he goes to war: wide-awake, with fear, with respect, and with absolute assurance. Going to knowledge or going to war in any other manner is a mistake, and whoever makes it might never live to regret itβ - Don Juan