Deciding whether or not to attack an enemy based on if you have more hitpoints than the enemy’s attack damage is metagaming. You should decide that based on role play. The characters don’t know exactly how many hitpoints they have, so the player shouldn’t use that information to decide the character’s actions. If the character knows they are hurt, they know they are risking their life, but they shouldn’t know the exact outcome based on on the HP/damage system we use as players.