You say most of my suggestions don't apply because you play only 12 creatures while my list plays 26.
In fact, you definitely have to put more creatures!
Part of my suggestions (move bounce spells to sideboard etc.) have the goal to make room for more critters.
It's true that you need some maindeck removal, but I would
opt for other stuff like for instance
Dismember.
As for
Boomerang, I admit I didn't get your point on why it's preferable to
Echoing Truth, but anyway there are so many better options that you can for instance pick
Chain of Vapor instead.