Also, a large litter might whelp a few days before scheduled, a small one of 1-2 pups might go a few days over. DO NOT estimate her due date just by the last date she was bred! Sprem can live within the birth canal for up to 2-3+ days so we estimate due dates on conception days, not breeding dates
I've looked @ before and after pics of this dog, and she does seem like she's in whelp to me. Maybe a small litter OR maybe carrying them high up under the ribcage, but if I had to make an educated guess I'd say she was bred. Is her vulva slightly somewhat swollen? It shouldn't be as large as it was during her heat, but a bred bitch's vulva will not shrink down to normal size. You can also palpate for pups, turn her over on her back if need be.
A few years ago we had an "oops" breeding that I thought would not result in a litter. The bitch was kept in good physical shape & is naturally very muscular, so I did not notice much weight gain at all until literally 4-6 days before she whelped FIVE pups!!! And keep in mind even that weight gain was insignificant, it was just her pups dropping, b/c she always carries her litters very high up. You can never tell with this bitch how many she'll have as she never gains much weight.
But 100% definitive way to know for sure if she has pups is to make an Vet appointment within the next 24hrs for an x-ray or ultrasound. The x-rays are about $150 over here, so should be lower everywhere else, lol. I would do the x-rays sooner rather than later, because if you do have pups and she only has one or two, there might not be ample contractions to push them out when the time comes. Labor may have come and gone already. So the faster you can get them out, if they are there at all, the better ...
... mama's have been doing this for eons on their own, she is already programed as what to do.
Take her temp at least 2-3x today, and if you start seeing it average out, you'll know her time is coming VERY soon! You might want some Nutri Cal on hand to help her through the whelping & give her a boost of energy if she only has a small batch. Good luck .....