Whoa – huge question! If you have missed one period and think you might be pregnant, don’t panic (or celebrate) immediately. It’s a reasonable thing to think, but periods can also be missed because of infection, nutritional changes, travel, and stress. If you take a pregnancy test and it comes out negative, you’d be wise to see your doctor just to make sure nothing is wrong. If your periods tend to not be similar/regular, medical attention might be in order. Reasons for irregular periods can also be low body weight, extreme sport, and even your diet in general. Have your doctor take a look either way!