You don't have to be married or sexually active to reap the benefits of NFP! I think the greatest fallacy of Natural Family Planning (NFP)/Fertile Awareness Method (FAM) and the Catholic Church is that it is not taught or encouraged pre-engagement. There is so much more to NFP than just pregnancy! The body literacy that develops from practicing NFP/FAM is beautiful; similar to St. Pope John Paul II's Theology of the Body that explains the need for lust in our bodies, NFP/FAM teaches why our bodies do the things they do at different times of the month.
What is body literacy?
It is a better understanding of your body, how it works, and why it does what it does. NFP/FAM is based in charting several different things your body does, such as your resting basal body temperature, your cervical fluid, and different feelings/sensations that can be charted and attached to your different hormones. Instead of feeling like the only woman in the room who experiences cervical fluid, you learn that it's a sign of a healthy, hydrated body.
How does that help me?
A personal favorite YouTuber of mine (I'll link her here) frequently describes our periods, which is the beginning of a new menstrual cycle, as a monthly report card of our overall health. Your menstrual cycle is not just your period; different things that happen during your entire 28 (or 25) (or 33) (or whatever) day cycle can tell us a lot. Just because you aren't avoiding or trying to achieve a pregnancy does not mean that your body and your fertility don't deserve to be cared for and optimized. But you can't do that if you don't know what that it is or how to achieve it!
To be completely honest, there is a learning curve that comes with this. It isn't necessarily difficult, but it takes time and practice (like most skills) to cultivate good habits and make accurate inferences based off of the gathered data. If you feel called to the vocation of marriage, this helps you avoid the sexual frustration (or even risk of pregnancy) that comes with trying to learn this as a newlywed. If you aren't sure yet, there's no harm in charting and just learning about your body! If you have painful periods, charting can help you identify what is going on and show the doctors what you are experiencing.
Where's the faith in this?
Our female fertility is such a wonderful thing (Psalm 139:14); beautifully created in God's own image (Genesis 1:27). Even those 4-7 days of bloody shame known as our menses are not something to be ashamed of. We were made to do this; we are not broken because we bleed. NFP/FAM teaches us how truly wonderful and complex our fertility it is, but also how simple and beautiful a healthy cycle is. You don't have to be married to learn about and celebrate it!
You can start by charting through an app like Kindara, doing research into the variety of methods the Church approves (sympto-thermal method, Marquette, Creighton). Your parish may also have a Couple-to-Couple league or other resource that may be willing to help you out. Don't let your vocation step on your toes; there are so many resources available and great resources out there to help get you started!