She isn't behind the vertical OR broken at the 3rd vertebrae... SOMEBODY did their homework right! I'm not a fan of Arabian showing because 90% of the horses are behind the vertical and they call in 'collection'... but your girl looks fantastic.
In the last two pictures her back looks a little hollow, but I think that is just the nature of their gait.
I hope you kick major butt!
(and I assumed it was a mare because I'm exhausted. So if it's a gelding, just pretend I used male pronouns! LOL)