Our universe has existed since 13.8 million light years after the big bang theory. So, we have been reciving lights in both directions since 13.8 million light years. That makes the lenght we have observed to around 27.6 million light years. But since our universe has been expanding that would make its size furthur more due to second law of thermodynamics. After precise calculations physcists has predicted its size to be around 46 million light years on the both sides of observation that makes its size 93 million light years. But this is what we have been able to observe so far. So 93 million light years is the size of observable universe. As universe keeps expanding we keep receiving lights and our observable universe keeps increasing.
But what is the size of Universe, we couldn’t observe. Its infinite.
What is the center of Universe. The point from where we are observing space is our center of Universe. Just like a tower could be a plan of reference fot a particular region, we can observe a lot from large tower. Similarly another tower could be a plan of reference or center of observation. But Earth is the center of Universe for us. Its could be any other planet, start or even sun. So, the center of observable Universe for us is the Earth. But for the whole universe we don’t know what is the center of Universe. Our observeable universe has edges around 46 million light years on both sides but The universe doesn’t have edges.
At last all I wannna say is that we are center of our own observations (universe), so is everyone and so no one is the actual center of the Universe.