HELP!!

I was two weeks late, and then got my period for three days, the third day was just spotting. And I've had really bad heart burn and been nauseous with bad cramps. Cravings and very sensitive. Anyone have a idea of what's going on? My fiancé and I have been trying to get pregnant but it never happens. And I don't want to buy another test because we've spent so much money on them!