At 385 ilevel there’s tons of content that is relevant to you for gear, but Island Expeditions are not it. Those are strictly for AP grinding. I’d suggest doing your 4 heroic islands for the rewards then be done with it.
But you should try to hop into heroic Battle for Dazor’alor for 400 gear, and Mythic+ 10s give 400 as well now, plus a 410 in your weekly cache.
Not to mention the first boss in BoD is very simple on mythic so you can get some 415 gear.
I’ve maxed out my Heart of Azeroth at 50 and killed the first 3 bosses of BoD in mythic and have a 418 ilevel, so you have plenty of content to hop into.
And 8.2 will be out in a few weeks, so that’s even more stuff to do, including getting flying.