As I stated before: if a definition allows exceptions, then what is stopping DWKs from being another exception? So, I will only address those points that have no exceptions among published True Dragons and compare them to DWK's.
1. Dragon Type: this one isn't even up for debate The Dragonwrought feat explicitly states this
2. 12 Age categories: All Kobolds have these, Dragonwroughts included
3. Warm blooded: True, normal kobolds don't fit this, but it is entirely up for debate on if Dragonwroght Kobolds are cold-blooded or not. They obviously have some blood link to True Dragons, the only question is just how much does this affect? We know it affects their physiology because of how they age and how they live longer than normal Kobolds as well as the change in type. The fact is, we just don't know. This is the one hangup for being sure or not.
4. Grow more powerful as they age: Well, DWK's don't get any weaker, and they do gain bonuses for aging, so they fit this criteria.
5. Live for over 2,000 years: DWK's have their maximum age determined by their Cha score. Given how much time it gives them to raise their score 2 points, they can easily live for over 2,000 years provided they aren't killed by something else.
6. Grow in size: WHAT LIVING THING DOESN'T??? if you meant grow in size category, it's still the same. Unless you're going to imply that a human infant is a Medium creature, of course...
Now, as for the others. I know a True Dragon that doesn't fit those criteria, and it's even listed in Races of the Dragon as being a True Dragon!
Yu Lung dragons lack:
wings (also lacked by all lung dragons but the Li Lung)
Frightful Presence (lacked by most dragons of Juvenile age or younger)
breath weapon
damage reduction (lacked by most dragons of Juvenile age or younger)
spell resistance (lacked by most dragons of Juvenile ageor younger)
immunity to an energy (lacked by Radiant, Force, Prismatic, Shadow, most Lung (Lung Wang & Shen Lung has), Chaos, Incarnum, Ethereal, Rust, Styx, and Tartarian dragons)
blindsense
But wait! They have Blindsense! Actually no, no Lung dragons have Blindsense. They have Blindsight, but that's a different ability.
So, we have an explicitly True Dragon variety that lacks all of those things, the same things, I might add, that DWK's lack.
Since we have an exception to all of those "rules", what is to stop a DWK from being another one?