This is my fourth cycle of using birth control but within the last month, I've varied by a few hours when taking it every day because of schedule changes. However I have never missed a pill. My boyfriend and I had sex without a condom the week before my period was suppose to come and he ejaculated inside me without knowing. I took a shower right away and took an emergency contraceptive within 15 hours after it happened. This is the week my period is suppose to come but it hasn't come yet. My period came sooner last time and I'm starting to stress that I may be pregnant. I feel some lower back pain and slight but not painful cramps. Nothing very distinct. Am I just paranoid or should I start to be concerned? What should I do?