The first day of my last period was May 12th. I have had nausea for five days now lasting throughout most of the day and into the evening. It is killing me to wait because I am very anxious to be pregnant. What is the possibility that this nausea is because I am pregnant?

Also, I purchased a first response test, which says I could test up to 4 days before my missed period. However, it is more likely to be accurate the closer I wait until my missed period. I am trying to decide when I should take it. Any advice?