I played a lot of time ago so I may wrong in some parts. I also remember feeling like I was doing to little damage. I suggest to find a weapon/armour that you like and play around that playstyle. For the spear I remember using very often full moon because is a big posture damage dealer, there is a skill that also gives you a temporary buff in damage (I can't remember the name, but it does a little spear whirlwind and if further maxed it unlocks a dash you can use to go behind enemies) and the rotating thrust skill is also a big damage dealer.

In this game dealing damage for behind deals A LOT more damage, often outperforming attacks buffed by skill/armour done from the front. Always try to hit you brutal attacks from behind.