I know sorcerers have little known spells, but don't you want illusions since you want to be apart from the "usual" gnomish illusion-tricksters? Or simply have spells with "more effect" - understandable, since you are the only "mobile artillery platform" (spellcaster) of the group...
Posy's original conception was as an Evoker, really. Her first feat was Spell focus: Evocation before I realized how useless that really was...
I mean, Magic Missile has no save, so the +2 hardly helps, there are no good 2nd level Evocation spells, and in wasn't until 6th level that she got Fireball, where I used it for the first time. At 8th, she'll take Ice Storm; again, no save

. I took a Lesser Cold Orb spell just to have an Evocation spell with a saving throw!
But enough about Evocation! I really liked the idea of a sweet little gnome girl throwing around a lot of magic power. A big bang in a small package, as it were. It also takes her out of the traditional gnomish illusionist, which I did want to avoid. It sets her as apart from her community.
This accomplished a couple of things. First, although not exactly an outcast, Posy had to develop her people skills and charm to get along in Treedimple. It also tended to push her away from her community, and that pointed her in the direction of adventuring. While she misses certain things about Treedimple, I don't think she'd give up her adventuring experience to return.
Thanks for your interest! I'll have psychognome send you your Posybadge.
Oghma