You know there is a teeny chance you could be pregnant, but I wouldn't bank on it. Just, if you can be patient, see if in a few days your period comes, if not, consider taking a test for it. Even if it comes a little later dont' stress yet - stressing can also make for a late period- which can make you more stressed if you're afraid of being pregnant. It can be a vicous cycle! I can't tell you how many times I worried for nothing!