I think I had my first period a couple of days ago. It was a red-brown smudge that only lasted for a day and a half, so I'm not sure if it was my period. How can I tell?

Lots of girls expect their blood to be bright red during their periods. But it's completely normal for menstrual blood to be brownish. It's also perfectly normal for some girls to have their first period for just 2 or 3 days. Many girls will have a very light flow the first few times they get their period, while others have more.

How long your period lasts and how often it comes might change during the first couple of years of menstruation. That’s because your body might make different amounts of hormones from one menstrual cycle to the next. Other things can affect periods too, such as nutrition, exercise, and medicines. If you have any concerns about your period, talk to your doctor.