What am I doing wrong?

Not sure if this kind of post is allowed, I'm just posting here because I'm trying to learn more about how builds work in this game and because I really don't know what I'm doing wrong with my current storm sorcerer build. Here are some stats:

level: 6

race: drow half elf

class: storm sorcerer

STR 9 DEX 13 CON 15 INT 12 WIS 10 CHA 17

AC: 11

Spell save DC: 16

+13 spell attack

Feat: weapon mastery

equipment: Deathstalker mantle, Obsidian laced robe, watersparkers boots, amulet of misty step, ring of poison resistance, everburn blade

other party members are Astarion, Minthara, and Shadowheart (respecced to death domain cleric), I'm also in explorer mode so the game should be super easy already

I find that in combat I am always dying and I deal very little damage. The always dying I get because I'm using clothing instead of armor, but I went from clearing out most things easily until I got to the Underdark and Act 2, now I'm lucky to make it out of a fight with half health left and I've had to have someone else in my party res me at least twice now since level 5. I don't use a lot of non-damage spells, but I keep resistances in mind. I'm just wondering if I'm just getting some bad luck recently or if there's something really wrong with my build that I could remedy. If it is bad luck it's so consistent that it's starting to make the game frustrating and it makes me want to start over and play again as a warlock or something because I had no issues like this on my warlock character.