How do i take care of my nails without using any products?

I bite my nails a lot. The skin keeps growing up and up. I try to push the skin back down, sometimes bite it off. It grows back up again and comes up and up and now half my nail is covered with skin. My fingers look really fat and ugly because of this.

Even painting my nails makes it look ugly.

I need some tips and guidance on how to quit nail biting. I bite when im stressed or when im watching a show or movie.

Some guidance on how to make my nails stronger and look better. Is there any food I can consume to make it work? (Vegetarian only).

I dont really want to spend ant money on this process because im still a student and dont have my own source of income.

I appreciate any and every advice. Tell me what worked for you.