I think you hold off too much on using BT. Just comparing my logs to yours and I notice you only have 8 more BT casts, but your parse lasted over a minute longer. It might sound weird, but it's usually worth using BT on cooldown almost without even thinking about it. The exceptions are generally like so: A. SD procs, 2xRB procs (more an issue with the set), and Execute w/o being Enraged.
Other than that, though I might be missing something, it's good practice to just use it basically on cooldown.