We’re assuming you aren’t sexually active because then there could be trouble. Otherwise, nothing to worry about. According to Dr. Lisa Masterson, a Beverly Hills obstetrician and gynecologist specializing in adolescent medicine, “It’s totally normal to be irregular the first year or two that you have your period.” It takes your body that long to get into a regular schedule. “Once your body is used to the monthly changes, you’ll be right on track,” she says. If the irregularity continues or becomes a problem for you, make an appointment with a gynecologist. She’ll be able to offer some solutions.