So My Boyfriend And I Have Unprotected Sex Pretty Regularly,

So my boyfriend and I have unprotected sex pretty regularly, I got my period January 7th and it ended on the 12th. On the 5th and 6th I had little spotting. Then the day I got off my period my boobs began to be sore, my lower back hurts, I would get cramps, very tired, my boobs also appear to be bigger in size. I took a preganancy test but it came back negative. Is it possible I could be pregnant?