You know, it could be so many things. My Mom, although much older than you, was loosing her hair, and to make a VERY long story short, she had a benign tumor on her pituitary gland...that was also pushing on her optic nerve...it had gotten quite large. The pituitary gland is a small gland, but an important "sex" gland (for secreting hormones, etc)...and can cause hair loss. Simple daily stress would not likely cause your hair loss...unless you have some harsh chemicals on your hair. I would think a thorough check-up with your Dr including blood work and maybe an MRI of your head, could be in order. Don't worry, almost ALL tumors of the pituitary are NOT cancerous. But, can cause enough trouble!
Go see your Dr if it worries you.