If you think all I posted was a poem them you should go back and read the rest of it.
Your bitch may well be pregnant, as most bitches will only accept the dog (unless forced which is cruel) when they are 'ready' to be mated. This is often around day 10 - 12; I have had bitches produce when mated on day 7 and day 30. At around 2 - 3 weeks the first sign is often a hardening and pinking of the nipples, and the bitch tends to become a bit more lovey dovey'.
Bitches can 'miss' i.e. not be pregnant for many reasons, so even if they 'tied' i.e. the dog was held inside the bitch she can miss. Some bitches can produce a litter after a slip mating, when the dog enters the bitch but does not tie; the ejection of semen as he thrusts is sometimes enough. Sometimes a bitch 'takes' on the first mating, sometimes on the second or third; there is no way of knowing as the sperm can live inside the bitch for up to a week, which is why some bitches can produce puppies with two different fathers, as the eggs can be fertilised by sperm from two different dogs.
You can scan at about day 28 (this doesn't have to be by a vet, there are several people around who provide this service). Worm her (I use Panacur liquid 10% which is given from day 42 until 2 days after whelping.
Basically it is a case of wait and see, no need to increase food or decrease exercise, keep things as they are until about week 7 or 8 when you need to up the protein levels (feeding complete puppy food to the mother is recommended) but don't let her get too fat or she may have trouble whelping. The last litter I helped whelp was a Shih Tzu and the first was a breach birth and had to be helped out, or else the bitch may have lost all the pups and died herself. Hope you have someone on hand to supervise the whelping. (let your vet know when it is imminent). Trim around rear end or pups could be strangled.
The Book of the