I don't really know all that much about birthing kittens, but is there any possibility that there is still one inside? If she's stopped eating and growls when you touch her tummy- I would think that there is something seriously wrong- call her vet- explain that you can't pay until payday- they might take a look at her before then.
Aligator79 brings up a good point. There's a chance that she has either retained a placenta or might possibly even still have a kitten in there. Either way, you need to get her to a vet ASAP or you will lose her. It's not normal for a cat to not eat after giving birth. Usually they are absolutely ravenous after the birthing is over and they have had a bit of sleep.
I know you said that you don't have the money to go to a vet right now, but in this case, you've got to try to borrow it from someone or try to get your vet to credit you until payday because if she's not eating or drinking, she is not going to be able to manufacture milk. If she's not producing milk, obviously the kittens will die unless you take over the feeding duties yourself with a bottle. With a litter of seven that's going to be a LOT of work. PLEASE do right by this cat and find a way at any and all costs to get her to a vet ASAP.
Ghilly
Did you witness the births? If you feel gently along the stomach area, and there is one inside, you can fee the hard lump of it's head. A partial placenta remaining is trickier to find by feel, the smaller the piece, the less possible.
The best you'd be able to do is force feed her a KMR mother's milk type supplement, but anything left inside will within days cause infection to set in. If she's going to the litter box a lot, then it's possible that she has internal bleeding or the problem mentioned above. Kitty will confuse the need to "remove" the remaining material with the need to go to the bathroom.
She should get checked asap. Check for free vet services in the area (call the local animal control for any numbers, or shelter).
i agree with savas.....or elese u can give her boiled milk with some water mixed in it.