Am I pregnant?

 I'm about 6 days late for my period. A week before my period was supposed to start I had a little bit of spotting when I went to the bathroom. I brushed it off because I didn't see it again. I've just over the past couple of days been feeling nausea at night and somtimes when I eat, but I haven't thrown up. Also my boobs are sore not to bad but definitely noticeable! I'm usually never late, I've never missed a whole period. I've taken 4 tests and they are all negative!! Please tell me what you think is going on here because it's driving me crazy! Thanks