Could I be pregnant?

1. Average Cycle Length: 27 days.

2. I had sex on November 27th. That was two days after my last period ended (Nov 25th). According to this app, I started ovulating on the 29th of November.

3. I am on the third day of my missed period. December 20th.

4. I have taken a pregnancy test. It said I wasn’t pregnant, but my period was still late. So I’m nervous about that. Online it said that you should take the test around 10 days after you’re missed period because you’re sure to have detectable levels of the pregnancy hormones by this time. Should I take another in like a week or two if my period still doesn’t decide to make an appearance?

5. I was not able to take a plan B pill or anything of the sort.

The eve app is always spot on, when telling me when to expect my period. So I’m very worried.