Use six characters ! The game is designed for that many , thats why you're finding it challenging.
Icewind Dale is very battle oriented therefore you will need a healer, at least two fighters (could do with 3 , depends on your style) a mage and a rogue (mixed class)
I usually play with
Fighter
Barbarian
Wizard
Sorcerer
Druid
Rogue
But there are so many combos , you could exchange extra spelling character for a Bard for example.
It is a great game, with some challenging battles so just start again you're not that far in.








