@martin
IMO, with the exception of being born and bred in Britain, English becomes a second language if you speak it with accent.
Whenever accent gives you away, you should know that you're ESL. In your case, I wouldn't consider you as ESL simply because you came here very young and passed through the American education right from elementary, high school and college, you basically lost all your accent at a very early age.
I don't have any evidence to back this, but I think if you came to the states after 18, it will be hard to get rid of accent.
To the OP, I'm also ESL and the only section I really struggled with is BEC simply because of the WC, but I made it and it feels good. I will advice anyone to start with FAR, REG, AUD and take BEC last.
AUD was tricky but the good thing about it is that you don't have to be a seasoned auditor to pass it.
REG -63│ 84!!
BEC- 59│70│ 71 │78!
AUD- 75!
FAR- 87!
Mass-CPA