It sounds like he's acting like a puppy (well, he still is one); he wants attention and he wants to play. And like all puppies do naturally, he uses his mouth to get what he wants. Even if the attention he gets is negative (swatting at him, squealing), that still looks like play--watch a couple of young dogs tussling. Why should he quit what he is doing if it works (for him)?
Take a look at this thread; there is a lot of good information on it. https://www.dobermantalk.com/puppy-c...biting-me.html
It's mostly written for little dobershark puppies, but the basics are the same.
These are the main concepts:
1. Take away the attention he gets from biting.
This is where crates are useful. If he bites, he goes away in the crate for a couple of minutes. Every. single. time. No yelling, pushing him away, or swatting at him. No grabbing his muzzle, sticking your hand in his mouth or squealing. Just tell him "no bite" and calmly and politely remove him from your presence. A crate is very helpful; if you don't have one, dog-proof a room as a timeout place for him. You can even teach him to go to his bed and stay there until he is released (which you will do once he's calm, basically). Leash him so you can get to him to put him away easily.
2. Manage him so that he can't bite and chase.
Leash him when you've got kids around that he's likely to try to chase. Teach your kids not to run and squeal around him, not to tease him--if the kids are too young to understand that part, they shouldn't be let loose with your pup. You can also teach him a good "drop in place immediately (down) and stay there until you're told you can get up" command. You teach that when he is calm, obviously, but once you've got that command absolutely firm, you can use it if he is starting to get too wound up.
Always, always supervise any time your dog and kids are "loose" together.
3. Give him something to do to use up that excess energy.
That's a start...give the thread above a read and see what you can come up with. Questions?? We love to put our two cents in--just ask away.
Welcome to DT! I see you've already gotten the part about posting pictures--he looks a cutey pie.