The fleshwarper is a 10-level PrC from Lords of Madness you might look into - he's designed as an item crafter whose familiar gains abomination abilities every other level (and stacks for familiar abilities). It's also a d6 and medium attack progression class with only 1 spell level lost, so your familiar will actually take a few hits and hit reliably at the mid-levels - and he gets an exp pool for crafting grafts, so the familiar can have a few grafts without you losing experience. The text indicates that you can enter at 6th as an adept (
), despite the crafter feat required needing 8th level due to skill prerequisites before you can take the required crafting feat, so let's assume the skill requirements were lowered and you can enter at 6th.
Here's an alternate build that gets +12 BAB, 5d4, 10d6, and 5d10 HP, 19th level Wiz casting, and 15th level familiar advancement (OK, so it loses 2 NA and 1 Int). This build gets the familiar shared Shapechanges and PaO's, and the character is actually playable, if not particularly awesome.
(Note: the build below assumes that your familiar gains aberration traits without losing its base dragon traits, since otherwise the dragon familiar feat is a bad choice)
NG Changeling Abjurer 5/Fleshwarper 10/Abjurant Champion 5
1st char: Bonded Familiar (PHB II)
1st familiar: Hummingbird, he won't do much yet except buff your Init by +4 (Dragon mag.)
1st bonus: trade that Scribe Scroll for a fighter feat like Improved Initiative or something.
3rd char: Improved Familiar (great, now you've got a celestial hummingbird, yippee)
5th familiar: we move on up to the air elemental!
5th ACF: Changeling Substitution level
6th char: Craft Graft (prereq, but we're crafting stuff anyways!)
6th familiar: holy crap, it's an aberration air elemental!
7th familiar: whoa, now it's an aberration memphit!
9th char: Enspell Familiar (as you said, by now it's safe to stay home while your familiar travels around kicking butt for you)
12th char: Dragon Familiar (pity about the 13 cha requirement though)
12th familiar: aberration silver dragon!
14th familiar: aberration gold dragon!
14th char: retrain Improved Familiar for Combat Casting (wasted feat for Abjurant Champion)
15th char: retrain Improved Initiative for MWP: Longbow (or find a way to sneak in a martial weapon prof. for abjurant champion)
15th char: Craft Wondrous Item
18th char: Open feat! Maybe Improved Toughness, your familiar still needs HP quite badly.
Here's the Familiar's Handbook by Dictum Mortum, it has some great advice (and inspired me to make my bard with a coure familiar!)
http://forums.gleemax.com/showthread.php?t=875062