Two positive tests and one negative-

I just took a clear blue test and it came out positive!!! My fiancé and I were thrilled, so I started chugging water and went out to get more. I took a first response one and there were two lines but one was very faint. After chugging more water I took another clear blue and it came out negative. It’s early on. I’m three days before my missed period. I’m just a bit confused by the negative result. Could I not have enough of the pregnancy hormone in my body for the last one to read it? Help!