Itsmaira, if you are still following this thread:
There could be a hundred reasons why one is losing hair. Being vegetarian is an unlikely reason, if you have a balanced diet.
At your age, significant hair loss is worth going to a dermatologist for. If you are a woman and your hairline is receding, off-hand my first thought is: hormonal imbalance. Perhaps check if testosterone levels are a bit high, causing some male pattern baldness--not at all unusual in women.
If you suspect stress, you can ask if they will check your cortisol levels in early AM, but truth be told, cortisol does fluctuate a lot. There are some things you can do to prevent stressful events from stressing you out too much, like meditation and getting plenty of exercise.Don't let your concern about hair loss be another stressor for you, get a checkup with a doctor, maybe there is some easy fix.