What does it mean when my period stopped when it wasnt suppose to yet?

Short period: It could simply mean that it is a short period. A normal period can last 2-7 days and be every 21-45 days

Not unusual: It is not unusual for there to be some variation in menstrual periods once in awhile; often without any identifiable reason. During a woman's lifetime, the duration of her periods may change, this could be a new pattern for you. If you have had unprotected sex, consider being checked for sexually transmitted disease which can cause changes in menstruation. Otherwise, don't worry.