Could I be pregnant?

Okay, so my last period ended December 30, and I haven't gotten one since or had my normal period symptoms which just include light bloating. My boyfriend and I have had sex since, and for the last week and a half I have had pregnancy symptoms. Ive had constant headaches, light cramping, major back aches/pain, nausea, feeling like I'm going to throw up throughout the day, sensitive to smells, exhausted all the time, and light bloating. I took 1 test, it was negative. Then I was late on my period then got spotting 2 nights ago, when I woke up it was the same then got a little heavier throughout the day. Today it was thicker, and doesn't seem like implantation bleeding, more like an actual period, but not my normal period which is usually very very heavy. It then all of a sudden stopped this evening. What could this mean? Is there a chance I could be pregnant?