When he nips at your hands you have to make yourself clear that it is this behaviour that gets him sent out of the room. I know he's big, so at this point I'd be using a harness and a leash inside. The very second he bites your hand, you say "no biting" you are up and out of the room with him with no fuss - stand quietly in the hallway or room, bored and blank and pay him no attention no matter what he does. You are a blank statue. You'll probably have to do this many times until he gets really fed up of being out of his favourite place. Let him back in, and the second he bites, you're both out again. He will make the connection from the bite, to the words and the punishment, but you have to be consistent. If you're watching your favourite show and he bites to get your attention, you still have to get up and do it, because the one time you don't, means you'll be back at square one. It will suck, but it will fix your problem (my sister in law had an Akita who had the same problem, and they have a very nasty bite, even if playful- but that's a long story and she was very agressive!).

I agree with the playpen idea too, but the second you use it as punishment for biting means that it will become a negative place and you want your pup to be happy and settled when you're not watching them.

My own pup (Yorkie) went through a phase of hand biting during play, I used the out of the room method with her. I did it for less than 2 days and she got the message, and hasn't bit or nipped since.

I promise it will pass! Hopefully you can get the vaccinations done soon and he can expel his extra energy on walks, and when you've made your rules really clear, you can expect to see more benefit and make a really good friendship. It might seem hopeless now, but you have a lot of people on here cheering you on, you can do it!