What did your doctor say about your period being off so long?
I'd go back and talk over whatever is happening with your doctor.

Is it possible that the first positive tests were an early miscarriage? There are very few things that will bring about a false positive, certainly fewer still that were bring up two.

Have you been having sex recently? Is there any chance that the light pink spotting could have been implantation bleeding?

Have you recently gained/lost weight? been very ill? under an incredible amount of stress? Have you been back to the doctor? What did the doctor say about your period and the tests when the blood test came up negative? Have you taken another home pregnancy test? How early into the possible pregnancy did you have the blood test and ultra sound?

Sorry but I don't think that anyone can be of more help until we have more information. Even with more information, we're not doctors. I think you really need to make another appointment to see what's up.

Good luck.

You could have possibly had an early misscariage but you most likely would have known.

Are you heavily athletic/into sports?