I'm 16, Had Sex Maybe A Week Ago With My

I'm 16, had sex maybe a week ago with my boyfriend, I'm on birth control and take it at the same time every day (portia-28) and my period was supposed to come three days ago (first day of placebos). Right now, I'm three days into my placebo pills and I have had minimal to no signs at all of my period coming. My CM is varying day by day from white and thick to light brown.

I'm genuinely scared that I might be pregnant. Am I? What're signs?