menstrual problems I m 23 years old , 134.5 lbs. & on the 23rd day between one period & the next, my last period ended on the 2nd of December & i feel i should have already started my next one by now, i am sexually active, i want to know if it s possible that i could be pregnant? & how many days should there be between periods, cause mine usually ranges from 18-20 days which is why I m worried. I also have epilepsy & take 2000 Mg of keppra, 400 Mg zonegran & 4Mg of folic acid everyday. I would just like to know a professional opinion, i know i NEED to take a TEST but before that, i just WANT a REAL opinion. Thanks