keep in mind that size is relative and that by smaller i also mean bigger.
would it not stand to reason that our universe is but a singularity. That is, inside the event horizon of a black hole, that infinite singularity chains exist linking each universe to a corresponding location in another dimension of space time, a continuum of cascading space time relativities. Material example: A small bucket with holes draining into a larger bucket with holes draining into yet a larger bucket with holes with the size of the holes remaining constant. The holes representing a singularity both consuming matter in our universe and expelling it into another and the top of the bucket representing the infinite existing "smaller" unviverses, a spatial singularity incomprehensible from inside the bucket, which may be why we cannot measure nor truly comprehend the size of the universe because there is no size to measure just lack thereof. black holes are represented by the internal portion of the holes consuming (matter and energy) from the bucket(universe) we exist in but not being able to expell it, and a white hole represented by the external portion expelling water into the next bucket but not being able to consume it simultaniously.
time always passes forward, as would explain why matter cannot cross back across either event horizon.

I will submit more as feedback is taken into account