Saying "you are the universe" is like telling a drop of water that it's the ocean. There are no drops of water without the ocean, and there are no oceans without drops of water .
Try to consider a drop of water and the ocean completely exclusively of each other. It cannot be done. Of course, an ocean is composed of droplets of water—there’s no issue there. But if you were to isolate a droplet of water, you don’t have to think very far to realize it came from an ocean somewhere. If you try to take the easy way out and say “well, the droplet came from a rainstorm”, you have to ask, “where did the rainstorm come from?” You’ll eventually get back to the answer “the ocean”.
Why stop applying the idea to the drops of water in an ocean? The idea applies to things you see every day. You cannot consider an individual human cell without eventually considering a human being. Nor can you consider an individual human being without eventually considering a human cell. And you cannot fully consider an individual human cell without considering the nutrients it needs form the environment. And you cannot consider the nutrients without considering the energy they get from the sun. And you cannot consider the sun without considering the hydrogen atoms making up the sun. And so on, and so on…