There was so much to read and i started to feel that I have read it all before, so forgive me if I gave up on page 2 and didn't read much further.
I want to offer a suggestion to make up some difference for that 2 ECL. I play an Aasimar who is currently sitting on a shelf collecting all his level 4 dust, and I will probably play him after Lexington's closure or when I can take a break from him as my next main, just to get him off the shelf and possibly out of the rotation. Let me start by saying, Insignia, the fact that you made it to level 13 since February - (what is that, 5 months?) - is impressively fast. Maybe I do it wrong, but not a one of my characters made it that high that fast. Lex took 1 year to make it to level 10. He's a four year old character and only level 16. My fastest leveled character was Zidonne, who made it to 20 in two and a half years. My oldest character is level 14, and was made in 2011 when I first joined the server part time. My point is, you're doing good - enjoy the journey and try not to let the destination be your driving force.
As for an objective offer to this subject, I have felt that the ECL is frustrating, but it isn't as simple as reducing the ECL or adding bonus slots or feats or skills, but abillities. Teiflings get Darkness, which has combat advantages at the bare minimum of what can be achieved with it. Aasimars get...... light. A useless spell that hedge wizards and level two bards get and can use by sneezing. I see no fair advantage there and it's acutally silly. I always thought there should be something more, and perhaps the racial abilities could evolve as you level up, perhaps turning from Light, to Searing Light, to eventually Sunburst or something like that. On the other hand, teiflings too would warrant an evolution from darkness, maybe to shadow shield or shadow conjuration.
Or perhaps we can discuss a balanced evolution of the racial abilities. The point being to make that 2 ECL seem worth it. As a few people have brought up, many, many characters do not even see 20. And the ones who do are the ones focused heavily on gaining levels and power before story.