My girl will be 6 weeks tomorrow and is quite slight normally. She already seems very heavy but at time appears to be ravenous and I am concerned she will get too big. I am reading that some say she should only be having 10% per week extra but she is wanting more. She is being fed on Arden Grange and as she is better on the lamb I have taken advice from their nutritionist  that the lamb is very high density compared to the chicken and suitable for her to stay on with the additional amount.

I have begun with her Panacur worming program now but as 9 years ago ( around 6 week stage I lost an entire litter we think to infection) I am totally paranonoid and as it is her first litter worrying about everything. She has had the first CHV jab with 2nd to follow later. The question is should I just feed her what she wants. She does normally enjoy food but is not a total foodie like her Mum.

After whelping she will very quickly start to drawn on her reserves ..so being on the well covered side is no bad thing.
I step up the protein, meat, offal, cheese, egg, fish but not any more carbs than usual.
If kibble fed they say one third more by whelping but that is way too simplistic......one pup or 14.... All have different nutritional needs.
I like to really FEED my girls.

I have always fed to appetite.  Like tooolz I like my bitches to have some meat on them, knowing how very hard their bodies will soon be working.  Knowing that bitches almost always go off kibble once pups are here (due to sore mouths) I give the sort of food they will be on once pups are here. 

I poach white fish and give steak mince, scrambled egg, tinned pilchards in tomato sauce etc.  When they are producing loads of milk they will be burning calories fast.  I hate it when I see feeding bitches that are skin and bone, they have no reserves at all.  I aim to keep my bitches in the same shape they were in prior to mating.

Snap. Have a bitch 6 weeks gone (Friday), ravenous and big already and I worry too. I never have done before, but her litter sister owned by somebody else had to have a c-section and all pups were dead. My mentor looked at photos of the bitch being pregnant and her opinion was that she had been overfed, was too fat and hence had problems. At the moment I am doubling the normal portions and adding a meal of chicken wings during the day but she is still starving, even trying to eat toys.

Thanks for the responses. Yes a bit out of character she has started to eat paper and socks even pulling out the wicker baskets we have in a cabinet as she know she will find them there. I think I will up her food more as based on responses up to half as much again if she wants. ( she does get other bits and pieces)
She herself comes from a litter of 14 surviving and her Mum gave me not an ounce of a problem but she is a different build altogether and being her first you worry they will not be able to manage.
I have her Mum's half sister here. She had 2 litters both were small litters and the first pup was large and born dead and obviously this is something I would seek to try and avoid.