Although the Heartwarder of Sune (Faiths & Pantheons) doesn't give Divine Grace, it is a good option for chaotic good sorcerers. Full spellcasting progression, +1 Charisma increase at every odd level, good Fort and good Will. Won't help for Ref, though.
Your quickest way seems to take two levels as a paladin of freedom, or champion of Gwynharwyf as you only lose two spellcasting levels.
Paladin of Freedom 2 gives you +2 BAB, +3 Fort, detect evil at will, smite evil 1/day, aura of good, divine grace, lay on hands (Charisma bonus x2, so 14 hit points).
Champion of Gwyrnrwarnwyrfr 2 gives you +2 BAB, +3 Fort, detect evil at will, smite evil 1/day, divine grace, furious casting, and, if you have at least 11 Wisdom, one casting of a divine spell each day among a short list. But since you said your Will saves are very low, I'm not sure you have an average or better Wisdom.
Paladin of freedom seems easier to make compatible with the Heartwarder (which is very nifty for sorcerers) than the Champion. And has no prerequisites.
Champion prerequisites are BAB +6 (you have that, normally, being level 15), 9 ranks in Intimidate (if you don't have that, it may take a few levels to get), and two Exalted feats, Knight of Stars, Righteous Wrath. One of which is basically useless by itself -- an "entry cost" feat.
BTW, the Heartwarder prereqs are: casting 3rd level spells, Chaotic Good alignment, Bluff 3, Diplomacy 6, speaking Sylvan, Reflex +2, Dodge, Mobility, Spell Focus (Enchantment), proficiency with whips, Patron Deity Sune (or whoever's the goddess of beauty). Heavy prereqs (four feats, except for bards who may start with whip proficiency).