I'm 20 Y/o And Me And My Boyfriend Want To

I'm 20 y/o and me and my boyfriend want to have a child together and we have been trying for 3 months with no results. I usually start my menstrual cycles on the 18th of every month and they are very painful , but for this month it started on the 9 th. I thought it was normal so I took some medicine for the pain and my stomach immediately felt sick, and I had to vomit. I took a pregnancy test 6 days before my expected period date, and it says not pregnant. What should I do take another pregnancy test or stop trying?