WElcome Annbo. Please read all the answers all ready given. Your puppy is not being vicious or abnormal. She is playing inappropiately. The best way to prevent her biting and growling and grabbing your pants is to anticipate this behaviour BEFORE it happens and direct her to a toy. You should be able to see this when it is about to happen.
I am heartened to see she was only 10 weeks old when you got her. Hopefully she was with her Mom and littermates till then where she should have learned good bite inhibition. If taken from them sooner than 8 weeks, the usual age for placing Labs, she may have a harder time learning to control the strength of her bite but she can learn.
How long will it take? Could be months. My Lab puppy did. I only got to cuddle him when he was asleep. Little devil. Adorable little devil.