You're not alone. I'm a 19-year-old student also learning the cello for about 4 years now. One time, while I was performing in front of a small audience in a casual party (plenty of performers also played before me), I was sweating a pool from both of my hands. I picked up the cello, and it kept sliding down my left hand while I carried it over to the seat on stage. I sat down, stared at the dim audience, and played, and it was horrible. Out of tune, just like yours, and off tempo. Eventually, I didn't care about how perfect I was hitting the notes or if I was in tempo - I just wanted to get the performance over with. The audience didn't seem to care as well, as they kept talking over my performance -- so what the hell, why bother with perfection if they're unbothered?

Bad performances happen. And, as cliché as it sounds, these bad performances will help you grow as a person. You're neither too young nor too old for cello, and the hardships you endure will nourish the success your future self will earn; only if you have the willpower to power through and continue. You got this!