I'm working on a changeling hybrid Wild Mage Sorc/Dex Rogue character for our upcoming campaign. The choice of class/race was for flavour reasons and not because I think its especially optimal although the dex/cha synergy is nice.

My group is fairly into optimising and so i'm concerned about some aspect of the build and was hoping some of the charop experts on this board could give me some help.

It's especially important that its viable at all levels because we're starting at lvl 1 to play through a modified scales of war.

Current stats at lvl 1 after racial bonuses:

11 STR
10 CON
18 DEX
10 INT
19 CHA

AC 16

Feats: Unarmored Agility +2 cloth AC

Powers: Burning Spray, Acrobatic Strike, Explosive Pyre, Dazzling Ray

There are some really good RP elements of the character that I love. The ability to shapeshift into any medium humanoid is awesome. He also has fantastic skills as both a party face and a thief. His stealth is not fantastic for a rogue but obviously shapeshifting nullifies the need for that a bit.

The combat concept is basically a melee sorcerer with the mobility of a rogue and some of the rogue's extra actions and bonus damage eg sneak attack.

I've done some playtesting and it seems like survivability might be a problem with a starting AC of 16. It also seems like the damage at later levels dies off because the dagger bonuses for weapon and implement no longer cross over.

Any ideas or suggestions would be really appreciated. No part of the build or character is set in stone.