What class for a ... kinda weird half-dragon ?

First of all, hello 'verybody. (my very first post !)

So, here's the story :

Imagine a classic bard. Like Elan. Well, maybe more like a way too much Belkar-influenced Elan. And half-elf.
This little bard, along his adventures, came to make a pact with an Elder Red Dragon. More precisely, the dragon made a pact with the bard where the bard became, more or less, his slave.
=> at this point, my bard started to work out a Dragon Disciple class (2 levels taken).
The pact kinda turned out weird and wrong, and the dragon and the bard shared bloods ; then he slept with a Black dragon, changed sex, got pregnant, and more important turned into a Half-dragon. (yeah, my DM is... special.)

My problem is that, according to core rules, a half-dragon can't go Dragon Disciple (except when level 10) ; so I figure that I shouldn't carry on that career. (my DM thinks I maybe could, but to me it doesn't feel coherent anymore).
I could, of course, continue taking bard levels (an option I seriously consider), but these do not reflect very much the PC the way he turned out to be.

I found one or two homebrewd prestige class dragon-related, but they pretty much go around the "riding a dragon" style, which is, in my position, not an option.

So, as my DM kinda take large liberties with core rules, I wonder if any of you know of a good class (or prestige class) that my DM would accept me to take, as a recently become Half-dragon who secretly wants (with his, or, her newly born black dragon son) to be neutral among dragons.

So if I got this, you want your transgendered half-elf half-dragon bard dragon disciple to find a new prestige class?

Why not Dirgesinger, from Libris Mortis? Summon some undead, as undead add to any crazy combination like this.

You got it right :)

I was looking for something maybe more anger, combat, dragon related, but actually, Dirgesinger is quite appaling... I'd never heard of that one before, it sure looks great. Worth a look.

(oh, and for the record, my semi-bard is Chaotic Neutral, and should really try her best to stay Neutral and not fall to Evil, for her own sake.)

Multiclass into Dragonfire Adept?

Maybe not the strongest option, but one of the coolest.