Could I Be Pregnant?

My period was suppose to come this week (5/10-5/14) but it didn't. I took a pregnancy test on Friday and it was negative. Before I peed on it, the test already looked negative so I don't know if the negative I got was a true negative. I've been really tired lately, my boobs are sore & I've been feeling a little nauseous here and there. Could I be pregnant?