First and foremost, wonderful post! I know a lot of folks don't say it but it's very cool seeing stories like this shared and getting that honest, heart felt perspective. ^_^
Part of what you mentioned is concerning, but not terrible because a lot of us have been in a similar situation; focusing on something that helps make life interesting and fun, after which it becomes the focus. However, unfortunately, nothing ever lasts.
The good news is that there's always something else out there in the world, it just requires exploring it a bit. Learning to take that first step into new adventures and trying things out for size, seeing how they feel, and continuing if/when something doesn't click. And then making it a habit so there's always a few interesting things in your life, because if you focus on one thing for too long then you'll get "used to it" and lost interest. Oddly enough, it's actually genetically built into us humans, lol. We're meant to lose interest in things after a time and find something new, because in nature that leads to becoming healthier and happier. For example: Ever stare into the night sky, at the stars, at the same spot and after a bit it just kinda "blanks out"? That's because the visual stimulation is so low that the brain literally shuts off the feed.
I suspect that if you were able to get 1-2 more hobbies you enjoyed in your life, it'd help make FFXIV more interesting for you when you return to it. I do my best to spend some time with other things before I circle back to the game, even though there's a lot within it that I'm thoroughly enjoying bouncing between.
For example, I'm not solely focusing on any one thing in this game and as a result I'm enjoying the heck out of it! I've been playing for almost 3 months and I just barely started Stormbringers recently, lol. While going through the story I was playing BLM (which I love), and between the story and doing side quests and once I was able, daily routlettes, I just suddenly hit 80! So I decided to start up a Tank and Healer job (GNB and AST respectively, both of which I also love), and I've already gotten those two up to 70 because I took a break from the story because I was enjoying learning them both.
(And I maaaaay have also started BLU because I heard it was cool, and it is!)
I'm sure you get the point, lol.
But the last part is the most important: I know it's not easy to speak to a therapist, but it's one of those things that if you're ever questioning your life, then it becomes incredibly important. I never liked it, but like I said above, it's just one of those other adventures that one can learn to roll with. The payoff is well, well worth it.