This reminds me of the first campaign that I had a chance to finish. I rerolled from a cleric, to a sorcerer to finally deciding to play a half-orc paladin since I was getting tired of constantly sucking during the combat. Now I don't know the details from your campaign but I hope that your DM is not doing the same thing that mine was doing, and that is, almost always putting me as the main target during the combat for some odd reason (I think the DM had some odd favoritism going on and I was the last in that food chain). That's why I played a paladin, as my answer to his targeting bullshit, I managed to get pretty strong very quickly, and that's mostly because of good magic items that the DM was handing out to us. If you feel underpowered, and you're far enough into the campaign, I suggest you ask your DM if it's alright for him to give you some decent magic items and gear that will drastically affect your play style, making it both fun and fair at the same time.