My gear only includes a +9 dex( 8 in slot + 1 from blood gem) over a +5 tome. Rest is my base 11. (again, lower than you)
Only using basic water stance. (another -2 vs. yours).
We pretty much have the same CHA so this bonus ain't factored....
So the only thing I can come up with is your gear.
You have a +9 item, I have +10 (Losing 1 to all saves)
You are probably missing +4 from Parrying (Found on my bracers)
You are probably missing +3 from Good Luck (Found on my Trinket)
You are probably missing +1 from Eldritch Resistance.
I know you want to boost your reflex even higher. These could help, and will boost all 3 at the same time.
On the other hand, any reason you want to reach the 90's?
Look nice on paper, but one of my other toons have 76 reflex with no fail on a 1, and never failed a save yet (havent ran 2 new raids on eE with him tho).
Also, I have no clue what is a healgolem you stated, but reading your stats, it sounds like a reinforced-concrete-wall healing bot. Am I mistaken?
If it's the truth, may I ask why use 3 feats for evoc focus? (you said you have esf:evoc). Coupled with 28 WIS, I fell like your totally waisting 3 feats, mostly on a build that doesn't have enough levels for implosion (and even if you had, Epic mobs would still die on a 1, regardless of those 3 feats). Your other (useful) evoc spells are no save anyway.
May i suggest the full mental toughness line instead? More SP to heal/nuke (if your build has some nuking ability, which I guess since you took light spell power) but mostly more crit chances, which is in fact the true reason to take this line. More damages + more chances to regen SP was an easy choice for me.
Personally, I found my build to be resistant enough as it is for eE, so I focussed more on offensive abilities.
Maybe because I pug a lot, but I've found it a lot more SP efficient to kill the mobs myself rather than to spam 3x more SP to heal people who doesn't have a third of my offensive ability.
I just don't like to think I'm a merc with (hopefully) better AI.