It looks like my cat is trying to kill her kittens!!!!?

She is only around 10 months old and her kittens are just over 2 weeks old. We didn't know she was pregnant when we had her so it was qutie a shock!!! She had 7 kittens in total and when they are trying to suckle, she growls and meows at them, sometimes she gets up and walks away after like 5 minutes of feeding them so im also worried they are not getting enough milk. About 20 minutes ago some of them were suckling and she was scratching them and biting one of the kittens heads!!! Does anyone heave a feeling what is wrong with her or have any advice as to why she is doing this????