You need to pick ONE method for dealing with his pulling on the leash and stick with it. React the same way every time. If he begins to pull, stop, call him back to you and make him sit. Then YOU decide when to proceed. If you and your boyfriend do this every single time, it will start to sink in. Start today! Do the same thing when he gets distracted, etc. Yes, it will look silly to passersby, but they don't risk life and limb when, a year or less from now, he's big and strong enough to pull your arm out of its socket!

As for him mouthing you, how do you react now? Do you immediately pull away and reprimand him verbally? Do you immediately substitute an okay-to-chew toy? What happens?

Obedience training will help - especially if, knowing that you have a shepherd/husky mix, you take notes, and repeat the exercises every day. For months. You've got to do this, because that combination is undoubtedly a smart dog with a bit of the husky "Selective hearing" which you'll need to overcome.

He's part Shepherd - he wants structure, and if possible, a "job." That can be anything for a simple task like playing fetch, to bringing in the paper (without chewing it) to picking up all his own toys - a busy Shepherd is a good Shepherd, and a tired Husky is a well-behaved husky!