15 days late. two weeks ago i had brownish discharge but went away the next day. i took a test and came up negative?

Anovulation/pregnant: Although the chance is low, you could still be pregnant so you should get another pregnant test in a couple of days. If you missed your menstrual cycle, and aren't pregnant, you may have pcos, a thyroid disorder, or another cause for anovulation. If you gained or lost weight over a short period of time, it may also cause your cycle to be irregular. At your age this occurs more frequently.