HELP! I need all the input I can get.

My period was supposed to start this past Tuesday(the 16th), and it has NOT. I had light spotting for 3 days, the week of the 8th. I mean light as in, there was a drop, only when I went to the restroom and wiped. my bf and I did have unprotected sex, and there was no pulling out, the day before my last period. I've take 2 tests, 1 about 4 days before I thought my period would start, and one 2 days ago, both negative.

Is it possible that the spotting was my period, or could my cycle be messed up from our sex last month? or could I really be pregnant. I'm kind of paranoid. I knkw it is ver unlikely to get pregnant the day before your period, but still.