I got my period after it was 20 days late could i have had a misscariage? i had unprotected sex often.

Miscarriage : In short, yes you could have had a miscarriage. Knowing your cycles is an important way to understand when you may be ovulating and apt to get pregnant. There are many options for inexpensive and reliable birth control available. If preventing pregnancy is important to you, you should talk with your doctor.

Very Possible: At your age, it's common to have an occasional irreguar menstrual cycle. However, it's also very possible that you had an early miscarriage. You're playing with fire and also placing yourself at risk for a variety of stds. Please use condoms to avoid infections ; please see your doc to initiate effective ; safe birth control. Don't get pregnant until you are ready! (school, career, etc...).