Question?

Monday all day I felt off time 3 pregnancy test was positive two the same one another 99cent brand. Went to the doctors that day still a positive result. I took two today the second line became light, I went to another doctor and they told me that I'm pregnant. But don't know how far I am and they did a U/S and they said that they can't see any baby. Plus I hand a period last week so can it be a possibility that I'm not? Or am I?