
Have just read your other post & it could be that the scan is negative because a pregnancy is too early to be detected. I would hold off giving her any medication, treat her as if she is in whelp then in approx 14-16 days repeat the scan as that would take her to approx 30-35 days if I've read your posts correctly ~ you said she was swollen 2-3 weeks ago.
It would be worth you joining your breed club & as others have suggested, buying The Book of The Bitch sooner rather than later.
I would also suggest getting your bitch eye tested now & then if it turns out that she is in whelp, to get your dog hip scored asap (as at 12 months he will be old enough to be done) plus any other tests that are available to your breed.
All the best