When I was in high school, I played in a rock band with my friends after school but I couldn't play in the school's jazz ensemble because all the players had to also be in the marching band which I didn't want to do. So when I got to college, I joined the jazz big band without having any previous experience playing in an organized jazz ensemble or reading intricate piano charts.
For the entire first year, I got lost in every tune, in every rehearsal and in every concert!
However, I loved it so much that I didn't become discouraged. I knew that I'd eventually "get it."
And sure enough, at some point in my second year, it became easier and easier until I could follow a piano chart with ease.
Hang in there and enjoy every moment 🙂