I Had Unprotected Sex 3 Weeks Ago, He Pulled Out,

I had unprotected sex 3 weeks ago, he pulled out, I was on my last day of my period at the time, I take the pill but I skipped one a week before but took it the morning after I skipped it the night before, he had been drinking before we had sex. I took a pregnancy test 2 days ago (6 days before my period is supposed to start, it was one of those early response ones) and it was negative. I'm having yellow cervical mucous and my period is supposed to start in 2 days. What is the chance I'm pregnant? I have a hunch about it and I'm freaking out! Am I just over thinking?