Pregnant or birth control?

Maybe TMI but I had birth control implanted in my arm about 2 weeks ago, and had unprotected sex the same day, but we stopped halfway through and he didn't finish. I was supposed to get a period one week ago and haven't had any blood or cramping. Is this a symptom of the birth control (known to have unpredictable periods as a side effect), or could I be pregnant?

I've always had regular periods otherwise.