I've been using the combined pill for at least 3 years now. I flew from London to Beijing on the 1st of November and arrived the next day, missing my pill. I then took two. Coming back on the 10th, I arrived home on the same day and continued taking the pill normally. On the 15 and 16th, I had sex with my boyfriend. On the 20th, I was a couple of hours late in taking my pill. Today is supposed to be period day, but it hasn't shown up, despite the fact that it's usually like clockwork. It it possible that travel, different diet, jetlag, stress etc affected my period or is it more likely that I'm pregnant?