I was on lo loestin Fe for three months and it caused my periods to occur every 11 days. My dr. told me to switch to sprintec the following Sunday even though I wasn't done with the loestrin pack. After being on sprintec for five days me and my boyfriend had sex using the pull out method. My period is now a day late and I'm only on week three of sprintec. How possible is it that I'm pregnant? I regret the decision and realize how stupid it was... just really nervous and scared. Someone help!