There are lots of reasons why you might miss a period. In the first year or so, it’s common for periods to be irregular.
You might have two periods in one month, or several months without a period. Stress, extreme exercise, or diet can also be reasons why you miss a period.
If you’re worried about missing periods, or have had sex and think you might be pregnant, you should speak to a trusted adult or see your OBGYN to find out.