Pregnant?

Okay so my last period started on December 12th and only lasted three days. Since then I’ve only had sex three times on Dec. 16, 27, and 31. On the 16th we didn’t use a condom but he didn’t come, and the other two times we did use one. I am also on birth control. For the past week or so I have been very nauseous quite often but haven’t vomited. I’ve also had a tiny spot of blood here and there when I wipe and an occasional cramp. My boobs might be a little sore, but not anything out of the ordinary. My period is due in two days but I’m wondering if I should take a test. My boyfriend thinks I should but I just don’t know. Do you guys think I could be pregnant?