Two negative tests, but two days late. Could I be pregnant?

We had unprotected sex twice this cycle, once during the fertile period, once after it. I am two days late on my period - felt it coming on the day before, but it didn't come. I'm not usually like clockwork, but not always irregular either. In addition I have been constantly nauseated for about a week, and to the point of vomiting since the day before yesterday. Could I actually be pregnant despite the negative tests.