The key to answering your question lies in the word you used, "everything." Things exist. And, things exist in a place.
It is true that "things" are moving away from each other in space.
However, no one ever said that space is expanding, only that the things we can observe in space are moving away from each other at a very fast rate of speed.
Space is, as far as we know, infinite. Scientists and astronomers using the very finest optical telescopes that there are have been able to observe objects in deep space at distances of 13 Billion Light Years in all directions from the Earth. With Radio Telescopes they have been able to detect objects in Deep Space that are 40 Billion Light Years from Earth in all directions.
Now I do not mean to imply that 13 Billion or 40 Billion LY is the maximum extent of Space by any means. It is, however, the limit at which our technology fails to produce any useable information. In the future, perhaps some new developments will enable us to "see" farther, or "listen" farther than our current equipment designs permit.
Having said that, it is beneficial for those people trying to understand SPACE to make a serious attempt to write down the distance in Miles that is represented by the statement
"13 Billion Light Years." Write it down using all of the significant digits and do not use short cuts like powers of ten. If you do this, you will begin to understand the enormous distances that are involved in just the range to the fartherest things we can "SEE" with our eyes and cameras (equipped with all kinds of computer programs for enhancement). And, space continues on way beyond that, we just can't tell how far...
Since the Universe is a collection of things, and we can only see a portion of the "things" (many, many more things exist), we don't even know how big the Universe is.