I missed my period

Valerie
Hey my name is Valerie and I'm having a serious issue and I need some feedback.... Im having a late period this month and it was suppose to come on the fourth but it didn't. Last month it came on the fourth and I started taking prenatal vitamins after my period around my ovulation date on the 21st and now this month I'm 3 days late. I don't wanna go get a test so soon but I've been feeling very crampy lately and it feels like it wanna come on but don't I even try having sex but nothing comes. I'm very scared this is the first time something like this happen...