Did you hit all the settlements? Check your map and look for unexplored cities/settlements. There can be additional quests there.
Did you complete all the hunting trials? (You say "did the hunters," but I'm not sure what that means)
I'm assuming you did all the Cauldrons and Bandit Camps.
The cup/collectibles don't give skill points. I don't think the Vantage points do, either, although they'll give you XP of course.
Otherwise, maybe you just have to do more combat and get more XP. I remember topping out the skill tree well before finishing the game, because I never used fast travel and walked everywhere. That meant I did a lot of fighting.