I'm on HBC, and recently noticed something odd: my period used to start like clockwork on the first or second day of the placebo (Monday or Tuesday). About three months ago I skipped the placebo because I was going on a vacation and hoped to skip it entirely, but all I did was delay it by a few days. Ever since then, my periods have been late, starting on Thursday or Friday. It's giving me and my boyfriend heart attacks, I'm always on the verge of buying a pregnancy test! Is this normal?