please help

I know I'm gonna get hate or rude comments but I don't care I'm afraid. I'm 17 years old and I'm a junior in high school. I recently lost lost my grandmother and things have been crazy at home. I have been with my somewhat boyfriend a year now although we broke up for a while when my grandmother passed. I have also been on the pill almost two years. I had my period about maybe two weeks ago when me and my boyfriend had sex and two days after and now I'm deathly afraid I'm pregnant (White discharge and lower back cramps). I did take my pill the wrong day but it was the same pill for that week. Am I over reacting?