What Are The Chances Of Pregnancy Post Unprotected Sex?

i am 44 years old my LMP was Dec 17,2015.I had sexual intercourse last Dec 27 without withdrawal and 2nd inter course was jan 2 but withdrawal.right now I'm waiting for my period.I did ultrasound today and my lining was 14mm.is it possible that I am pregnant.no sign of pregnancy no tenderness of my breast,no vomiting,no nausea.everytime I had a period I am taking pain reliever due to severe lower abdominal pain.pls help me.