Hello, This Is Embarrassing But I Am A Bit Scared

Hello, this is embarrassing but I am a bit scared and confuse. I had unprotected intercourse on December 6 2015 but my friend the guy I was with use the pull out method and I also took a morning after pill the same day. Then on the 19th of December I got back with my bf and had unprotectedintercourse with him we didn't use no protection at all. Well I took a pregnancy test on the 26 of December and I wasn't pregnant I took another pregnancy test on January 4th and I wasn't pregnant until the 15 of the December the test was bearly showing a double line. My question is how long does it take for someone to get pregnant unfortunately I don't remember my last menstrual period I have irregular periods. Please if u can help me to find out when I conceived?? Thank you