I don't think healing numbers in total are a good way to evaluate your healing in M+. Every run will be different. Some groups need you to sustain 15k HPS to simply get through the dungeon other groups need 10k. As for throughput mastery goes a really long way in helping you keep people up more effectively.

As for others saying jdotb isn't great to copy I'd disagree. Druid is probably the easiest non-disc healer to easily weave damage in because your kit is so dependent on hots and you have a decently good "oh shit" heal in swiftmend if you need it. You can learn to heal first then dps/heal later but you're only going to find the times where you're punished for catweaving by catweaving and it's probably more effective to learn to both heal and catweave at the same time.