what fields of science would i need to refine to further my understanding of our universe?

Physics...and you will also need a love of mathematics.

If you study physics at college you can then decide whether you are more interested in "going small" and study sub-atomic particles or "go large" and study astrophysics.

Asking this question shows that you have the curiosity required to learn more about the universe.

When I was young, I found msthematics boring. I did not yet understand its beauty or importance. Then I had a couple of teachers of mathematics in my college years that did an amazing job of helping me to understand math and it opened up science to me in a new way. Science starts with mathematics. In one manner or another, all science relies on some branch of mathematics. Start slow and be patient when learning math. It. takes time to become proficient in math; however, learning math will open up the universe to you because math is the language of science. The specific branch of science that deals with the nature of existence is Physics. You can also begin to learn the basics of Physics without knowing advanced math. In fact, I would highly encourage you to explore the basics of Physics and all the sciences early. The study of science will fascinate amd amaze you. (But remember to keep up with math because it will open up so much of the universe and science if you hang in there and pursue it.)