im sure she will start eating soon. as it is normal and congratulations on the new kittens im sure tilly is a very proud mother . she may not be eating because she still feels sore after giving birth so just give her some tym and i am sure it will be ok
keep posted x
you could also try giving her some Nutri-Cal for cats ( avail at any pet store, like $5) i give it to Icis when she gets picky about food, she loves it. It helps with calories and energy, and is a safe supplement for cats off there food.