It sounds like youre doing it right.
Part of MP management is knowing when to ask for support.
Weather it be more heals from SCH or MP Songs.
Also, try to use Shrout of Saints as much as possible.

I personally use my first SoS at 90% MP. Then at ~70, 50, 30 (asks for MP song at this point), 10.
In turn 4 I can use about 3-4 SoS. I don't really run out of MP or step into the danger zone I would say (~20%) until the 2nd Dread is dead.