What causes periods to stop but random bleeding from the vagina im only 19 and i haven't had a period since i was like 17 and i haven't engaged in sexual intercourse yet.

If : If you are having "random bleeding" then you are probably having irregular, light periods. There are other reasons besides pregnancy that can cause a woman to miss a period such as: stress, diet, excessive exercise or a hormone imbalance such as with a thyroid disorder or poly cystic ovarian syndrome. Since it has been 2 years since you had a regular cycle, you should see a doctor to discuss your symptoms. Good luck!