It must be very hard, given you're pregnant at well, but he's very young Bun. For biting a very loud 'Ow' - loud enough to surprise him, then turn your back on him or if that does'nt work, scoop him up and put him behind a dog gate or even a door for a few seconds until he calms down. Message being - biting = end of game. The growling and biting harder is probably him responding to your challenging body language and tone, as he would to a challenge from a litter sibling. He things you want to play harder.
If he's just play biting but not too hard, try saying ow and shoving something he can bite in his mouth then telling him he's a good boy - so he learns what he can and can't bite. With dogs you can't just tell them what they shouldn't do you need to show/teach them what they should/can do.
House training. I'd ditch the puppy pads and take him outside every 15 minutes to start with, gradually increasing until you get a feel for how long he's going between wees. You need to wait out there with him until he goes and ignore any invitations to play until he has gone. Then when he does go make a huge song and dance about it, tonnes of praise and a really tasty treat. If he goes indoors, don't react at all, just interrupt him and take him outside - even if he's pretty much finished. Then clean up without saying anything. Are you using a biological pet accident cleaner, like Simple Solution? If not, he will still be able to smell where he's gone before, even if you can't and using anything other than bio cleaner will actually spread the scent out and encourage him to go there again. If you haven't got any pet accident cleaner, biological washing liquid or powder in very hot water will do the job until you can get some and you need to thoroughly clean all the areas he's been.
Are you taking him out and about much? Carrying him to all sorts of different places is exactly what he needs at the moment. It will make him aware of the big wide world and wear him out trying to process the enormity of it all.
He should be having periods of manic puppy behaviour interspersed by long naps. If he's not napping, that could explain why he's getting so manic and you probably need to enforce some quiet time to encourage him to sleep. If he doesn't have a crate, perhaps a well wrapped hot water bottle and blanket in his bed?