I had sex three days before I was "supposed" to get my period. I'm not on birth control but we used a condom. My periods are relatively regular but not exact and now my period is around a week late. I've already taken a pregnancy test that came back negative. This past week I was on spring break and drank a lot of alcohol and traveled 12 hours from home... Do you think the alcohol, change in diet, and lack of exercise this past week could mess up my period in conjunction with stress? Thanks in advance!