Help im scared and nervous!!!

okay so I am like 8 or so days late I've had heartburn really bad been moody and kind of queasy with diarrhea and I bought a preg test but when should I take it?? I'm so scared it will say neg !!!! any advice? I have also been kind of tender in that general area like when I have sex it feels tender and when I lay back on the couch it is tender also?!!