As a current college student myself, I can attest to the fact that you are certainly not the only one struggling to manage. A lot of young kids nowadays feel the pressure to 'do it all' while making it look easy which is often not the case so try not to be deceived/be too hard on yourself. I also struggle with low self-esteem, which can be tough to manage when you're constantly being tested/graded/pushed, it helps for me to focus on the small victories and remind myself that the only way to improve is to fail a few times.
Your age provides you with a unique perspective and different experiences that the younger students do not have, an advantage that I am sure will show through positively in your work if you embrace and allow it. It was a big and very important step when I realized that comparing my accomplishments and goals with those of the students around me was only discouraging me, but rather embracing my background and how far I have come makes me feel a bigger sense of accomplishment and the sense that all of my hard work is indeed paying off.
Best of luck