It isn't unusual for someone to miss a period and then to go on and continue with normal periods. A period only happens if the woman has ovulated 15 days before it, and it isn't uncommon to skip an ovulation sometimes. This can happen for a lot of reasons, including stress, or body fat dropping, or even just because. But if you want to be sure on the pregnancy question, just hop over to the Dollar Store and get their pee-on-a-stick pregnancy test. They are inexpensive so if you're worried, it wouldn't be a total waste of money.. But it doesn't sound like you're pregnant. :)