12 wk old miniature poodle is aggressive and draws blood?

I need help. I adopted this little girl poodle at 8 wks old , when i brought her home I went to hand her the food bowl and realized i forgot to put her worm medicine in it. so i pulled it back to add the medicine and she attacked me like a ravage beast,, and left me bleeding,, after a lot of patients and determination I finally got her to not bite when i took her food away. But now she is acting out at random. For example she had gotten into the bathroom garbage and when i bent to take it form her she attacked my hand viciously, growling ,and biting leaving my hand bloody. I have a 6 yr old son whom she has bitten on his back and stomach while he was trying to play fetch with her, using a toy he bought her. He was sitting on the floor and when he picked up the toy she bit him in his stomach.hard. and then a few days later it happened again when he tried to pet her she bit his hand and when he turned away she chomped into his back,,He really cried as her bites hurt badly.. My son begs me to keep her although he is afraid to play with her, or else i would have found her another home already, I know she is only 12 weeks and small but her teeth are sharp and are guaranteed to draw blood most of the time, You must understand this is not playing she is doing this viciously.. I know the difference as i have had several dogs and currently Have a 12 yr old Pomeranian who has never bit since being trained not to, I have had him since he was 8 weeks old. .. I dont know what to do..she is fed 3 times a day just like us, and she gets snacks.these is no reason for such aggression , this dog has never been mishandled or abused, we treat her like part of the family and love her.. but I personally am starting to wish i never got her, ,, there is a very fine line between me keeping her and me giving her away.. I can not allow her to keep biting..she has been to the vet for shots and checkup and there is nothing wrong with her. she is just mean,,My question is : can you suggest something that i can do to make her understand biting is wrong and will not be tolerated,. and can you give an explanation as to why she is so mean and aggressive.. please keep in mine that my other dog dont want bothered with her ,he turns his back on her, so i know he is not instigating her to so this,