Period or pregnancy spotting?

Sarah
So I'm 19 years old and had unprotected sex (we used the pull out method) on December 27th, almost 4 weeks ago. I was supposed to get my period on January 14th but I never got it and immediately started to panic. It took me until I was 8 days late (today) to take a pregnancy test and it came up negative (thank god) a few hours after I took that test I thought I had gotten my period but it's pretty light and not constant. I did some research and saw that "pregnancy spotting" was something that's common in the early stages of pregnancy. Basically I just want opinions on whether I have a reason to worry or if I'm just being overly paranoid. Thanks in advance :)