Poe 2: Problem when facing low level bosses and using skills that are not the most used.

I run out of mana potions when facing bosses due to lack of damage when being at low level... even so I have no way to increase the damage to skills that do damage over time, I took everything I could in the tree and bought the best weapon I could, I didn't waste it and even so I ran out of mana with the boss at half health... they should make the potions have more charge and that all last a certain time when activating them if they don't want the player to get frustrated... for having one more problem than they already have when trying to dodge and not run out of health potions.
Does it interfere with classes that use mana to defend themselves? Add that if they use that node that reduces the charge or amount of the mana potion.