We went through the same exact thing. First of all, know that it is totally normal. He hits and growls and bites because he doesn't have words to communicate and he is trying to tell you something. I know it seems like a crazy way to say "hey mom" but he knows it gets your attention. He is just frustrated because he doesn't know how to communicate what he really wants to tell you.
Good advice we were given that worked for us:
Gentle touches - when he hit, you calmly say say, "no, baby, we don't hit mommy. We use gentle touches." Show him while you speak. Gently touch him. Take his hand and stroke your face with it." If you respond with anger, pain or frustration, it simply compounds the problem. He needs to see that the gentle touch is much more effective. Remember, since he was born, he has learned that screaming gets your attention. This is just an extension and until he gets his words, he will do whatever it takes.
No bites, kisses - when he bites, you calmly say, "no baby, we don't bite mommy. We give kisses." Give him a kiss. Ask him to give you a kiss. Stay calm, smile a lot and show him lots of love.
Time in, not time out - remember that he is doing this as a means of communicating something. Fast forward 10 years and imagine you had a child with a terrible stutter. If he couldn't get the words out, would you send him to his room and give him a time out? No, you would be patient and try to help him say what he wants to say. That's what you need to do here too. Try to figure out what he is trying to tell you. You may not figure it out right away. It may be weeks before you figure out that he bites you to say he likes it or he is full. But eventually you will figure it out and this too shall pass.
Good luck.