If I remember it right, your companion gets a certain % of the exp your earn from killing monsters.
This means that you don’t need to go to the lower level areas to level your companion since you won’t get any significant exp from those areas anyways.
Just bring him along with you when you’re grinding, dungeoning, or running quests at your level and he’ll eventually catch up by leeching on whatever exp your earn when killing mobs.
No need to bring meat at this point since he’ll only be leeching from you, and he won’t die anyways. You’ll only want to start feeding him once he’s able to contribute some significant damage to keep his stamina and HP up.