My resting heart rate is 90-100 lately and i dont know the reason? maybe stress? im 19 y/o female and this scares me. should i be worried?

No worries: Your resting heart rate still falls in the normal range - stop worrying. Look for ways to better manage your stress: regular exercise, limit caffeine, time for recreation, meditation, etc all go a long way in helping us cope.

HR: HR can range from 60-100 in the normal range. If however, your HR is normally lower and now is elevated, this can be due to several reasons including increase in stress, anxiety, increase in caffeine intake or cocoa intake. If you have any symptoms of palpitations, chest pain or shortness of breath, you should be evaluated.

Here are some ...: Heart resting rate of 90-100 per minute may be "normal" for less physically active people if having been able to conduct personal & occupational chores and tasks at a reasonable pace without short of breath. So, you may consult Doc to assess your general physical fitness, ability, and lifestyle as well as to ensure you're free of anxiety, insomnia, overactive thyroid, drug misuse, etc. Best wish..