Pregnant?

I'm on the pill. Today is a Thursday, I was suppose to start my period on Tuesday. However on Tuesday I only spotted, I haven't started at all and there's no spotting since then. I am usually very regular and am under no stress. There's also an odd sent down there that I've never had before. I took a pregancy test this evening but it was negative. So I'm wondering maybe since I did it at night it's not as accurate. That maybe I should take another one to see if I'm pregnant but I just have no idea what's going on with my body.