Ill try and help although I haven't played WoW in 2 years I just came back to legion.
You mainly want to swap between the rogue and the priest whilst your Druid cyclones the priest and cyclones and roots the rogue, its your job to stop some fears on your Druid, he needs to be well positioned to displacer beast some fears, and you want to charge/hamstring the Priest when he tries to go for fears, when you are stunned your druid should be displacing some fears or rooting, cloning the the rogue.
If the rogue sits on your druid, you should just train the rogue, so your druid can clone/root stuff, if the rogue sits on you most of the time, your druid should be freed up to clone and root.
Basically you want your druid to rotate clones and roots as often as he can, so he is able to do this, you must keep both targets slowed, you should use Storm Bolt for this matchup, and he should be travel forming/displacing a few fears. use the root on your charge to stop some CC.
Now against assassination Rogues, they don't have a lot of CC, but have a lot of damage, try and mitigate this with some clones when you need some breathing time, your Druid should be well positioned for this and far from the Priest.
The essence is really stoping as many fears as you can on your druid, he should avoid some also with travel form, dash and displacer Beast, you should root the Priest with charge and hamstring to stop the fears, if the rogue is on you, then your druid should be able to avoid most fears.
HTH, maybe someone with more experience in current game can help you better.