Not to criticize your choices, but we still have 12+ days left to finish Springvale. Even with all the other stuff going on, you should still be able to finish it with plenty of time to spare without using any flasks.
Personally, I only use the WE flasks during Atlantis Rises, to max the loot. I had managed to bank 20 flasks from the last one and now have 101 axes and 82 dragon attacks (plus 300+ arrows and 200+ bomb attacks) saved up for the challenge event.