My bitch is also at the 7 week stage, and is also not eating :-D I have tried everything from left over mince to sardines, to rice pudding. All she ate was the mince. Today I asked my son to collect some frozen uncooked dog mince (chicken) from Pets at Home. She wolfed it down ;-) hurray :-D :-D I found something she will eat. ;-) She did this with her last litter and had 9 puppies so I'm not too worried, but it is a pain when you know they should be eating :-D Little and often is the way to go for the last 2 weeks. The tummy just can't hold a huge amount of food.
Oh, forgot to add: she is also much more clingy thatn normal, and is growling at the other dogs if they get too close, unless she decides she wants to play

;-) She sat in the whelping box today and just looked at me :-D Then she came out and hasn't been back in it since ;-)