nervous please help!

Hello, I'm kinda nervous. So I lost my virginity on June 2, and it was unprotected (I know I was stupid). He did not ejaculate in me because after a minute it was just really hurting so I made him pull out.I did not have the money for a plan B pill. I do not know if I was ovulating or when my last period was because I'm very irregular. I took a pregnancy test 18 days after intercourse and it came up negative. I was wondering if it could have possibly been a false negative and I am pregnant?