pregnancy chances?

Abbie • 🇬🇧🇦🇺
My boyfriend and I had sex on November 16th, we didn't use a condom, he didn't come while having intercourse (I am aware of the chances of getting pregnant from precome). I am on the pill, but didn't take it the night before so I took it after we had sex and continued the rest of the pack as normal. 
I got my period December 6th, it was heavy, lasted the normal length of time; 5-6 days and contained clots. According to my pill pack my period should've come today, (they always arrive in morning) however there is absolutely no sign of it. 
What are the chances of being pregnant if the last time we had sex was in November?