your query is vague. You are 19, and at this age your hormonal cycle is not yet established, so having irregular cycles is normal at this age and this may remain for few more years. In irregular cycles or normal cycles, the period must never be excessive, or for more than 5 days. as you are bleeding since 20 days, it would be better to go to a gynecologist and get treated. Some tests like thyroid test and sonography may be done to rule out some problems