I play as a Shadow dancer/rogue and part of the issue is picking your battles. Rogues are great at doing serious damage via sneak attack, and doing almost everything outside of combat thanks to their skills.
So on to decide how you fight.. the question is are you a striker or are you a supporter. Strikers go for the leader while the party takes care of the rest, while supporters try to use their sneak attack to aid their allies by aiding what they are dealing with. You sound like a supporter, so you seem to want to be the last line of defense between them and your range/spell caster.
Honestly , if you have a high charisma, then go for magic through rogue talents after fast stealth. Keep going in shadow dancer to get respectable at spells while being respectable at melee.
If your sorc becomes fireball happy, then being in the middle of the worst isn't terrible. Your reflex save with evasion should mean you are perfectly fine when your own team decided that you make a great target and that should keep most of the enemies at bay.
and flank flank flank. The shadow will help with flanking, but can be a little annoying when he is the only thing dealing strength damage and everyone else targets HP.
Sometimes the best option for a rogue is to hide and strike when it is best and not be fighting right away.