I took my bitch to the vet today to see if he could confirm a pregnancy.  She would have been 6 weeks today, but he says he couldnt feel any pups in there and that she was not pregnant but then the next thing he said was she could be carrying one high under the ribcage and she could suprise me with one!!  He said he was of the 'old school' where he preferred to 'feel' for pups rather than scan.
What i really want to know is if i go with the thought she's not going to whelp will it cause any problems if i don't increase her food intake now and then she does have one??  Also i wanted to know if she was so i could get the DIY fanatic other half to build a whelping box.
Is there a possibility do you think that she is?  This would be her first litter and when she was mated the mating took place twice on one day with the tie taking place both times and lasting for 10 minutes each time. She looks more rotund than usual and she seems different in her mannerisms but then he did say it wouldnt be unusual for her to have a phantom pregnancy.  .
Thanks for any advice given.

I think if there are doubts you must get her scanned. I had doubts about one of my bitches, and on getting her scanned we discovered one puppy only. This may not seem like a bad thing, BUT what often happens when a bitch is only carrying one puppy, is she takes too long to give birth and you end up with a distressed bitch and one dead puppy. Don't leave it any longer, if you know there is a pup or maybe two puppies you can then arrange with your vet to be aware you may need to have a Ceasarian performed on your bitch.