I Recently Got A Positive Pregnancy Test. Only One Of

I recently got a positive pregnancy test. Only one of four, the rest were negative. I am having all the pregnancy symptoms and this will make my fourth child. My first, one and only girl, I had the same problem, no positive urine tests. Pregnancy was verified by blood test and ultra sound. I have an appointment in November, but I am just trying to ease my mind. Is it possible that I am pregnant?