Crazy mood swings, BFN HPT

The past week I have been ridiculously emotional and moody. It's driving DF and I both insane. My stress level is the same it's been for as long as I can remember. After talking to a friend, I decided to take a hpt. It was a BFN. I can't think of any reason that I would be so emotional or moody other than being pregnant. Should I wait a week and take another? Or should I try to figure out another reason for the sudden moodiness?