
It's a great shame that it has got this far, as it would have been so much easier to just get her the injection when you had just guessed that it may have happened.
A visit to the vet pronto, and a scan is what I recommend. You don't have much time to buy everything you need for whelping.
If it's 7 weeks ago, it's perfectly viable for her to whelp in a weeks time. You need to have enough money put aside for a C-section in case she has been mated to a dog much larger than herself.
Oh - and get her spayed after? :-)