I had 0 issues with Stone Vigil as healer, did not wipe once yet
And I was quite surprised because Cutter's Cry was a hot mess (oh so many wipe that I though I was a terrible terrible healer)

Don't think you are a bad healer, at worst you just need to practice more and keep your skills and equipment updated
It is also hard to find great synergy sometimes in DF

the succeed/wipe is sometimes out of your hand but Tank and Healer are the one who will always get accused first

here is the pattern:
  • Tank blame the Healer
  • Healer blame the Tank
  • DPS blame Healer and/or Tank

Don't worry too much, do your best and keep trying
If you have good LS/FC, ask for some help as well ^^