If you are reasonably certain your dog didn't hook up, it is likely she is having a 'false pregnancy'. My female lab went through this on her last heat and it can last up to 9 weeks after she comes out of season. She will exhibit many of the physical signs of pregnancy. Keep an eye on her or you can simply make a quick visit to the vet.
The other option is wait ~70 days and see if anything 'pops' up. :shocked:

:grin: