I used the same. And he was dead in one night. Took us like 35 wipes. It would be dead much quicker but we had some not needed deaths all over the place.
Was unlucky with procs, but yea did some healing.
http://worldoflogs.com/reports/rt-d8...=12682&e=13126
If you get more procs in the time the blessed healing is up on your target it is somehow stacking, so the healing from each ticks are higher and higher so all you need is just spam flash heals to not drop this buff on the boss (my uptime was 32,4%).