Pregnant or just a missed period?

We are both 20 and have been dating for 6 months.  We have been having unprotected sex (no condom) but I am on the birth control pill.

I broke up with him 2 weeks ago. I was supposed to get my period on December 13th, but I am still without a period. I tested when I was 4 days late with my period and it came back negative. Was that too early ro test?

Could I actually be pregnant?

I had some spotting for one day, but nothing like a normal period... Also, I was not stressed before ovulation, so it is not that I wouldn't think. And I was on my placebo pills and even was off the pill for a good almost 2 weeks and still nothing (after the breakup).

What is going on...?

I am never late..