my last period was march 24th how many weeks am i?

[Mercedes]

I had sex april 13th and i have a thirty day period which means that my period should come on the 23rd of april if im not mistaken but im not cramping like normally i cramp a weak before then i come on i have Just been real hungry nauseated some days and now my breast are starting to become real sore. I have to pee Lot i took a test but negative, but also my stomach is getting bigger by the day....my baby daddy has twins heavily in his family can it be a possibility that its twins and the pregnancy test is Just not picking up because i never miss a period and im really wanting a baby but im not stressing cause i know that causes complications...But a woman knows when her body is changing