Negative test but I'm sure I'm pregnant?

Chelsea
Ok so this would be my 2nd child if I am pregnant and i need advice as my period would be due today and yesterday I started spotting and experiencing cramps, my boobs are really sensitive and sore and my periods are usually so regular every 4 weeks and I normally suffer bad with cramps and back ache but at the moment I'm just having slight cramps that come and go and also the bleeding I have is a lot lighter than usual and that comes and go too. Does it sound like I am pregnant ? I just done a test and it was negative should I do another soon? I think it's still too early to tell but working out from my last period I would be about 4 weeks which is when implantation happens and they are the s