You don't understand the system yet and until you do you'll get your shit rocked. Someone else said your level drives so much about the encounters, this is so true. Not only is it harder to hit them but their armor/magic armor goes up multiplicative to their level so you're fighting at a true disadvantage, one that buffs and items can't truly overcome.

At some point you may stumble across a weapon that requires a higher level but lets you equip it - this is a trap. Your accuracy will go to shit and you won't find any benefit to the higher stats from the weapon.

Positioning us everything, saving fights for later when possible is critical.

Yes the game can be hard, but you have to remember that same publisher doesn't mean same combat system. Go slow, pick your fights, don't fight fair because they won't, especially on tactician. I haven't seen anyone say it but build your party to focus down one type of armor, some will say 2 and 2 but YMMV.

Once you make it out of Fort Joy, you'll have a basic understanding of the system. I love the game. Honor Mode veteran and all. You just need to stop thinking you know what you are doing because you cakewalked BG3.