Help .????

Lucy
Hey guys , so I need help or advice 
I got my period last month on the 1st of September I ended my period on 5th , my period are always irregular but I had unprotected sex on the 11th 17th 18th twice and 20th , I've  taken two pregnancy test and both have come out negative I took one 13 days after I had sex on 24th , and I also  took one the 21st  which both came back negative 
What should I do ? 
Am I not pregnant then