I believe in God, I'll say that upfront.
The big bang theory, which most people believe, states that the big bang was the universe expanded from a point of singularity. And space didn't grow around the singularity. The singularity itself expanded. Thus, there is no middle. Imagine the universe as the surface of a sphere that you stretch, only 3d instead of 2d. If you expand the sphere, the surface of the sphere does to. Now draw some dots on there. As you expand the sphere, the dots move apart. However the surface has no center. You can look at any point, and it looks like the center. Everything moves away from it, but that happens anywhere on the surface. This is why you will never find a center to the universe. Everywhere and nowhere is the center. Everything is moving apart.
To answer the inevitable question of what I believe in terms of Big bang vs. God, I will say this: God ways are incomprehensible to us mortals. Do we ever look at rocks and consider the soul of every particle in every atom in the rock? Do we consider how they can just move themselves when god commands? Where does this energy come from? What even is the nature of energy? The possibility of the bing bang is as incomprehensible as the nature of the priesthood. Natural laws are the laws Our Father in Heaven uses to accomplish his works. The priesthood, spirits, and energy itself? all natural. We just don't understand. God may have used the big bang to create our universe, or the universe is eternal, like him. Humans can't understand eternity in the slightest. Our mere mortal minds think in terms of something starting and ending, but not everything does. We cannot comprehend the nature of truth with our limited minds. My dream is to be righteous enough for exaltation so I can one day know understand the mysteries of God for myself. I still have a long way to go, of course.
Anyway, that took a sort of tangent there at the end, but I don't really know how else to answer a question so fundamental about our existence. Hope this helps!