I've Missed My Period For About 5 Days Now, And

I've missed my period for about 5 days now, and I'm scared that I'm pregnant. My stomach hasn't gotten ang bigger, and I don't have any symptoms of pregnancy, the last time i had sex was about 5 weeks ago, right after my period ended. Yet, I don't have any signs of pregnancy. I still have yet to take a pregnancy test. I have looked on some websites and they say that I could have missed my period due to many other reasons, and yes I am on birth control pills to help regulate my menstruation cycle. I have had fatigue, stress, and Imve been excersing a lot more lately. Is it true that I've missed my period because I am pregnant?