confused

So I am late getting my period 3 days late to be exact. My husband and I are not actively trying. But I am late I have a VERY regular cycle so this is concerning and confusing. I bought a 1st response test and it came back negative is I took it around 11:30AM but it wasn't my first morning pee.. last week I was cramping and I was spotting which again isn't normal for me and having slight back pains and my boobs are tender.. other than having a cold I feel fine.. any advice? Or thoughts? I've decided to test again if I haven't started my period on Monday which would be 7 days.. Is this a good idea??