Our black lab, who was abandoned and we adopted him into our pack of 7 dogs is pushy, constantly challenging even us for dominance. He will just tear into one of the other dogs even when they’re giving submissive signals. He’s the strongest willed and most volatile dog we’ve ever had and that includes pit bulls and cattle dogs. He had his equipment still intact and we are fairly certain that he was owned by a young female who dumped him (unbelievably he had a collar tag still). He’s used to having his was and chafes at any control.
We deal with it and keep a tight reign on him and make it work. My point for all of this is that there are actually a lot of large male labs who are like this.
Dogs, like children, usually reflect those who raise them.
Hang in there.