The universe doesn't really have a shape, nor is there an outside, to the best of our knowledge.

According to the big bang theory, which is the best theory we currently have and is supported by the most data, the universe expanded out of a zero-volume and infinite-density state about fourteen billion years ago. The expansion, however, was not expansion into formerly empty space. Rather, space itself is expanding, and drove the particles that the universe contains apart.

A good analogy would be to think about balls of fuzz on the surface of a balloon: blow up the balloon, the balls of fuzz do not get bigger, but the balloon does, so the fuzz gets farther apart. The same thing seems to be happening to our universe with the fuzz being galaxies, except that the universe is expanding in three dimensions, instead of just two. As far as we know, the universe has no edge; it continues in all directions forever.

Now, the part of the universe that we can see does have an edge, which is caused by the finite speed of light - we can't see anything farther than fourteen billion light years away because that is all of the time that light has had to travel. That volume, of course, is a sphere, but outside of that is more universe.

The simple answer is nobody knows what is outside of the universe. The more correct answer is that the question itself makes no sense. This doesn't mean it's a bad question, it's just a question that can't possibly have an answer (as far as we know). It's the same thing as asking "What's north of the North Pole?" Everything that we know exists is the universe, it is the fabric of existence itself. You couldn't go outside of the universe because time and space are properties of the universe. So there is no such thing as "location" outside of the universe. In the same way, you can't look at the universe from the outside, and see what shape it is. Space around us appears to be a sphere, but, that's a limitation of the fact that we can only see a certain distance away. Some people make guesses about how other universes could form outside of ours, but, since these guesses can't be tested by evidence, it isn't actually science just guesswork. There is a lot left to learn about the universe.

This does not answer your question, but here is a great video on how the known universe is organized and where we are in it! I hope you find it interesting!