Could I be pregnant? Help! I'm only 16

So I do actively have sex with my boyfriend, but we use protection every time. However, I've been on my period for 4 weeks straight, so somethings up. I'm going to the doctor soon, but could this be a sign of pregnancy? Has this ever happened to anyone else ?

Update: I didnt start new birth control or anything. Everythings been normal. Doctors appt is Thursday.