"In my purely amateurish understanding of how this theory works, you have a nearly limitless set of options to choose from this moment forward - but once you've made that choice, there's no going back."
But, according to the subject of this thread, there just might be the possibility of going back. And, in the act of "going back," you've altered an apparently limitless set of options going forward, effectively limiting these options to only those leading to the outcome of going back. Predestination of a sort. Try to visualise this, not from the perspective of the "now" being left, but from the perspective of the "now" destination, which would not be in the past to those inhabiting that "now."
Not yet enough coffee to enable me to focus entirely on that, but I get the gist of your statement. Fascinating to ponder.